The Whitehead Torpedo consists of a cylindrical air-flask to which is attached an ogival head and a conical after-body, bearing the tail. The head contains the explosive charge, for use in action, or fresh-water ballast for use in exercise; the air-flask contains compressed air, the motive power of the torpedo; the after-body contains the engine and the controlling mechanism; and in the tail are the propellers and the rudder.

Air is compressed in the air-flask to a pressure of 1350 lbs. per sq. in., or ninety atmospheres, approximately, and the torpedo is launched from a tube, above or below the water-line, by air or gun-powder impulse.

The air-flask is of heavy forged steel; the other parts of the shell of the torpedo are of thin sheet steel, strengthened at various points by strengthening-rings and at the joints by stout joint-rings. The interior parts are generally of bronze, with a few easily accessible parts of steel.

Weight of torpedo with air-flask charged to 1350 lbs. per sq. in. and war-head attached, ready for launching (approx.)

845 lbs.

Weight of ditto in sea-water (approx.)

7 lbs.

Reserve buoyancy of ditto in sea-water with pressure in air-flask reduced to 1050 lbs. per sq. in. (approx.)

4 lbs.

{

Weight of torpedo with air-flask charged to 1350 lbs. per sq. in. and exercise-head attached, ballasted with fresh water (approx )

836 lbs.

Reserve buoyancy of ditto in sea-water (approx.) (Owing to variations in the weights of air-flask and tail sections, there may be no reserve buoyancy.)

2 lbs.

The torpedo is constructed in five sections, but is ordinarily dismounted and assembled in three principal parts:-

I. The Head, A.

II. The Air-flask, B, to which is permanently attached the Immersion-Chamber, B', containing the charging and stop-valves, K, and the immersion-mechanism.

III. The After-Body, CC', in which are the engine-room,

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C, the main shaft, E, and the steering-rod, S, and which carries the tail, I. In the tail are the top, bottom and side-blades, constituting the frame of the tail, the bevel-gears, G, the shafts, the propellers, UU, the rudder, R, and the vertical vanes.

The engine-room contains the main engine and the engine oil-cup, (not shown in the plate) the valve-group, V, the sinking-gear and retarding-gear (not shown in the plate), the steering-engine, F, and the locking-gear, L.

There are two interchangeable heads supplied with each torpedo, the war-head and the exercise-head, for use war and exercise, respectively. The head is attached to the forward end of the air-flask by twelve joint-screws.

The war-head, of sheet phosphor-bronze, is charged with approximately one hundred and eighteen and one-half pounds of wet gun-cotton and, is closed at its base by a bronze bulkhead secured by screws to a stiff, joint-ring of bronze in the after end of the head, against a rubber washer. In the bulkhead is a moisture-tap through which distilled or rain-water may be poured, when necessary, to make up possible loss of weight in the charge by evaporation. The stowage-weight of the war-head, that is, the weight of the shell and contained charge of wet gun-cotton only, is stamped on the bulkhead near the, moisture-tap.

Soldered in the forward end of the war-head is the primer-case, P, of brass in which is inserted the dry guncotton primer when priming' the torpedo. The forward end of the primer-case is recessed and threaded for the reception of the war-nose, W.

The war-nose, screwed in the forward end of the primer-case in the war-head, consists of the exploder, the mechanism for firing it on impact of the torpedo with the target, and the safety mechanism by which the firing mechanism is rendered inactive until, after launching, the torpedo shall have traveled through the water a safe distance from the point of launching.

The exploder, a, is a closed copper tube, painted red, containing 35 grains of fulminate of mercury primed with 4 grs. of finely mewled g.c., and capped at its forward end by a percussion cap. It is carried on a holder, b, screwed on the after end of the body of the war-nose. A hole in the center of the holder permits the entrance of the exploder from the inner side before screwing the holder on the body. The rim of the exploder seats on the body of the war-nose and is held firmly in place by the holder.

The body of the war-nose is of bronze. The firing-pin, c, of steel, capable of longitudinal motion within the body of the war-nose, is held in place, with its point clear of the percussion-cap of the exploder, by a shearing-pin, d, of pure tin, passed through holes in the body of the war-nose and of the firing-pin, keeping the latter from being driven in by the rush through the water or by impact with light articles in the path of the torpedo, before the target is reached.

Within the body of the war-nose, forward of the firing-pin, is the traveling-sleeve, e, of steel, capable of longitudinal motion to the extent allowed by the screw, f, entering the limiting-slot, g. The traveling-sleeve is threaded, inside, throughout its length and in this thread works the steel traveling-nut, h, which has a square hole in its center through which passes the square shaft of

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the screw-fan, i, of steel. The shaft of the screw-fan is retained in the traveling-sleeve, with freedom of revolution within it, by the screw, k, whose inner end projects between two collars on the forward end of the shaft.

During the passage of the torpedo through the water the square shaft of the screw-fan causes the traveling-nut to run aft within the traveling-sleeve until the nut bears against the forward end of the firing-pin when the further travel of the nut aft is prevented by the resistance opposed by the shearing-pin but the continued revolution of the screw-fan causes the traveling-sleeve to run forward to the limit of the screw in the limiting-slot. The screw-fan and the other movable parts of the war-nose are then in position, upon impact with the target, to force aft the traveling-sleeve and traveling-nut against the firing-pin, shearing the shearing-pin and driving in the firing-pin against the percussion cap of the exploder.

The length of the limiting-slot is such that, when the traveling-sleeve is run to its forward position, the square shaft of the screw-fan will have run out of the square hole in the traveling-nut and the screw-fan will revolve freely during the further run of the torpedo without opposing undue resistance in the water.

To insure against explosion by an accidental blow, the war-nose must always be kept, in store and while being handled, in its position of safety, with the traveling-nut run forward to its full limit in the traveling-sleeve. This is done by revolving the screw-fan in the direction of the arrow stamped on the body of the war-nose until stopped by the contact of the two stop pins, one in the forward end of the traveling-nut and the other in the forward end of the traveling-sleeve. In this safe position it requires a run, after launching, of forty-five yards, giving about thirteen revolutions of the screw-fan, before

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the traveling-nut presses upon the head of the firing-pin, and then a further run of twenty-four yards, giving about seven revolutions more, before the traveling-sleeve reaches its extreme forward position.

Holes, ll, in the body of the war-nose, in rear of the firing-pin, permit the free escape of water, avoiding cushioning.

The entrance of water to the primer, around and through the war-nose, is prevented by a porpoise-hide washer, m, interposed between the torpedo head and the shoulder of the war-nose, and by a disc of pure copper, n, .003 inch thick, soldered water-tight in the recess, p, in the base of the war-nose over the hole through which the firing-pin passes. Upon impact, the firing-pin perforates this copper disc and fires the exploder.

The exercise-head, of sheet steel, is ballasted, for exercise, by filling it with fresh Water and is closed at its base by a steel bulkhead secured by screws to a stiff joint-ring of bronze in the after end of the head, against a rubber washer.

It carries a primer-case, similar to that in the warhead, in the forward end of Which screws, against a porpoise-hide washer, either the depth-register, or the rolling-register, or the exercise-nose, X, to which may be hitched the nose-line for towing the torpedo.

The air-flask, B, is a hollow, forged steel cylinder, slightly tapered at the ends, with dome-shaped heads screwed and soldered in each end. A strengthening-band,

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Z, left on the inside surface in boring, is tapped from the outside for three screws for attaching the guide-stud, T. Over a hole in the after head is bolted and soldered the body of the charging and stop-valves, K.

The charging and stop-valves, in the forward part of the immersion-chamber and accessible from the outside, are wholly of bronze and the body of the valves is cast in one piece. The charging-valve, through which the air-flask is charged, consists of the following parts:- the charging-valve plug, f, to the lower side of which is attached the charging-valve, g, whose stem is free to revolve in the plug; the charging-valve seat, h; the check-valve, i; and the check-valve spring, k. An undergrade-leather washer is placed under the charging-valve and a porpoise-hide washer under the shoulder of its seat. The check-valve is ground in and is held up in its seat by the check-valve spring. When the charging-valve plug is removed for charging the torpedo, and the charging-pipe, b, fitted with a valve-end, a, and wing-nut, c, is screwed down in the charging-valve seat, a rib, e, on the bottom of the valve-end, a, presses down on the stem of the check-valve, thus admitting air to the flask.

Upon removing the charging-pipe the check-valve is closed by the pressure of the spring and of the air beneath it, and the charging-valve plug, screwed down again on its seat, effectually prevents any loss of air by leakage around the check-valve.

The stop-valve is used to close the flask, after it is charged and until it is to be placed in the tube for launching to prevent escape of air and consequent loss of pressure. It consists of the following parts:- the carrier, l,

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screw-threaded externally and capable of longitudinal movement along the female thread in the body of the valve; the stop-valve, m, whose stem is attached to the carrier but free to revolve in it; the stop-valve plug, n, and follower, and the operating-spindle, p, whose lower end, or shank, is square and travels in a square axial hole in the carrier, and whose upper end is held up in the stop-valve plug, free to revolve in it, by the follower which screws in the base of the plug under a collar on the spindle. Porpoise-hide washers are placed under the head of the stop-valve plug and between the follower and the collar on the spindle. The stop-valve is ground in. Turning the spindle screws the carrier down or up, seating or lifting the valve.

Air is conveyed from the air-flask to the engine, via the reducing-valve in the valve-group, V, Plates I and III, by a copper air-pipe leading from the body of the stop-valve above its seat.

The immersion-chamber is a short truncated cone of steel, riveted and soldered to the after end of the air-flask and closed at its after end by a bronze bulkhead, a. The shell is strengthened at its middle part by a strengthening-ring inside and by a stout joint-ring of bronze at its after end. The bulkhead is secured to this joint-ring, against a rubber washer, by screw-bolts and nuts, thus rendering the immersion-chamber air and water-tight.

The immersion-chamber contains the charging and stop-valves, K, and the immersion-mechanism.

Drain-holes (DD, Plates I and III) closed by screw plugs, provide means for draining the immersion-chamber.

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THE IMMERSION-MECHANISM.

The immersion-mechanism consists of the hydrostatic piston, the depth-index and the pendulum.

The hydrostatic piston governs the immersion of the torpedo during the run, and can be set for any desired depth within the limits shown on the depth-index.

The pendulum acts to maintain the axis of the torpedo in the horizontal plane.

The combined action of the hydrostatic piston and pendulum is transmitted by a system of levers and connecting-rods to the steering-engine and thence to the rudder to steer the torpedo to its set depth, and to maintain it in the horizontal plane at that depth.

The hydrostatic piston is a metal disc contained in a shallow circular recess cast in the center of the bulkhead, a. The after side of the recess is closed by a flexible rubber diaphragm, b, which permits water-pressure to act on the after side of the hydrostatic piston. The rim of the diaphragm is clamped, air and water-tight, against the after side of the bulkhead, by a bronze ring secured by screw-bolts and nuts. On the forward side of the piston bears a spiral compression spring, c, carried between two sliding spring-boxes in a bronze tube, d, cast on the forward side of the bulkhead. The after spring-box transmits the thrust of the spring to the piston. The forward spring-box is fitted with two lugs which project through longitudinal slots in the sides of the tube. Against the forward side of these lugs bears the lower fork of the forked bell-crank, e, by which the compression of the spring, c, may be varied at will by adjusting the depth-index, described in the following section.

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The motion of the hydrostatic piston is transmitted to the steering-engine valve-rod, f, by the hydrostatic piston lever, g, the upper connecting-rod and sleeve, h, the cross-lever, i, pivoted on the port pendulum-rod at, k, the lower connecting-rod and sleeve, l, the rock-shaft, m, and the locking-jaws, m'.

The connecting-rods and sleeves, h, and l, are made elastic by the interposition of a spiral spring in each sleeve to prevent sudden shocks from straining the system of levers and to take up the movement of the hydrostatic piston and pendulum when the steering-engine valve-rod is locked.

The rock-shaft, m, transmits the motion of the system of levers through the bulkhead by means of the air and water-tight stuffing-box, n, which is bolted to the forward side of the bulkhead, against a washer of thick paper. A screw plug in the top of the stuffing-box screws in against a porpoise-hide washer. The rock-shaft is ground in, in its bearings, and has two arms, one outside the stuffing-box, connected with the lower connecting-rod and sleeve, l, and the other inside the stuffing-box, connected with the steering-engine valve-rod, f, by the locking-jaws, m'.

By means of the depth-index the adjustment is made by which the immersion of the torpedo is controlled during its run. The head of the spindle, o, is accessible from the outside of the shell. Its shank is square and fits in the head of the adjusting-screw, p, whose lower end is supported by the socket-post, q. The adjusting-screw passes through the adjusting-nut, r, which has a collar upon which bears the upper fork of the forked bell-crank, e, When the spindle and adjusting-screw are

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turned the adjusting-nut is moved along the adjusting-screw, raising or lowering the upper fork of the bell-crank and causing its lower fork to compress, more or less, the compression-spring, c, against the forward face of the hydrostatic piston. The greater the compression of the spring, c, the greater the force opposing the water-pressure on the after face of the hydrostatic piston and, consequently, the greater the immersion of the torpedo before the hydrostatic piston will be in equilibrium between these opposing forces. The position of the rudder, when this equilibrium is attained, is slightly down, steering the torpedo in the horizontal plane against its buoyancy which tends to make it rise.

The index-sleeve, s, visible from the outside of the shell, is graduated on its upper face for feet of immersion. It is geared differentially to the spindle, o, and is retained in place within the body inclosing the gears by a gland screwed over it. When the spindle is turned, in making the adjustment for immersion, the index-sleeve revolves, showing by the coincidence of its graduation with a fore-and-aft line stamped on the shell, the depth at which the torpedo will run. The clamp-nut, t, is screwed down, after the adjustment is made, clamping the depth-index and making a water-tight joint, by forcing down the spindle against a porpoise-hide washer interposed between its shoulder and the inclosing body, which is riveted and soldered to the shell of the torpedo, inside.

In assembling the torpedo, the reference point of adjustment of the depth-index is for five feet immersion of the torpedo, The adjusting-screw, p, is turned until the after edge of the shoulder of the forward spring-box in the tube, d, coincides with a line cut on the side of the tube, marked 5, which gives the compression of the spring, c, that will balance the water-pressure on the

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after side of the hydrostatic piston at a depth of five feet. The depth-index is put in place with the mark 5 on its face corresponding with the fore-and-aft line on the shell of the torpedo. Starting from this point, the adjustment can be made for any desired depth by turning the spindle, o, with a socket-wrench inserted from outside the shell of the torpedo.

From the pendulum-supports, uu, secured to the forward side of the bulkhead, a, is suspended the pendulum-bob, v, by the pendulum-rods, v'v'. The pendulum swings in the vertical plane passing through the axis of the torpedo. The pendulum-guide, w, secured to the bulkhead, passes between the pendulum-rods and keeps the pendulum from swinging in a thwartship direction.

Through a brace, x, joining the pendulum-rods, passes loosely the checking-spring rod, y, hinged to the bulkhead. The checking-spring rod carries the compression checking-springs, y'y', the inner ends of which bear against the pendulum-brace and the outer ends against the checking-spring nuts, zz. By means of the checking-spring nuts the compression of the checking-springs may be varied to check the sensitiveness of the pendulum, retaining it from swinging in either direction until the axis of the torpedo shall have become inclined a small angular distance from the horizontal plane. The adjustment of the checking-springs is usually made to restrain the pendulum from swinging within an angle of inclination of the axis of the torpedo of from 3° above to 3° below the horizontal plane, thus permitting the hydrostatic piston to operate the rudder within these small limits of departure of the axis of the torpedo from the horizontal plane without interference by the action of the pendulum.

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The motion of the pendulum is transmitted to the steering-engine valve-rod, f, by the cross-lever, i, pivoted on the port pendulum-rod at k, the lower connecting-rod and sleeve, l, the rock-shaft, m, and the locking-jaws, m'.

The pendulum is limited in its total swing by the bulkhead, a, abaft it and, forward, by the strengthening-ring of the immersion-chamber, braced at its lower point against the force of the blow of the pendulum by the buffer-bracket, z'. Spring-buffers, w'w', ease the shock of the blows of the pendulum.

While the torpedo is in transportation a transportation-screw, put in place of the screw plug in the drain-hole under the pendulum, projects in a hole in the bottom of the pendulum to hold it steady.

The after-body, CC', is a truncated cone of sheet steel joined to the after end of the immersion-chamber by eighteen joint-screws. It is stiffened at its forward end by the engine-room cage, a stout frame of bronze, riveted and soldered to the inside of the shell of the torpedo throughout the length of the engine-room, at its after end by the forward half of the bevel-gear box, of bronze, riveted and soldered to the shell of the torpedo, and, at equal distances between, by two interior strengthening-rings.

In the forward part of the after-body is the engine-room, C, containing the main engine and the engine oil-cup (not shown in the plate), the valve-group, V, the sinking-gear and retarding-gear (not shown in the plate) the steering-engine, F, and the locking-gear, L.

Numerous openings through the shell admit water freely to the engine-room and give access to the interior in making adjustments. A large rectangular opening over

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the engine-room is closed by a plate called the engine-room door.

The after part, C', of the after-body is a water-tight compartment containing the main shaft within the shaft-tube, E, and the steering-rod within the steering-rod tube, S. The forward end of this compartment is closed water-tight by the engine bed-plate, M, secured by screw-bolts and nuts to the after end of the engine-room cage against a rubber washer. The after end of the compartment is closed water-tight by the tube flange of the tubes, E and S, secured by screws to the forward face of the bevel-gear box, G, against a rubber washer. Through the shaft-tube, E, and the steering-rod tube, S, connected by water-tight joints to the engine bed-plate and to the tube flange, pass the main shaft of the engine and the steering-rod.

The engine is a three-cylinder, single-acting Whitehead engine, the body of which, of phosphor bronze, comprises in one casting the cylinders, the valve-chests and air-passages and the crank-case. It is bolted to the engine bed-plate, (M, Plates I and III) by six holding-screws.

The three cylinders, AAA, radiate from the crank-case, B, in the transverse vertical plane of the torpedo with their axes 120° apart, and on the forward side of each cylinder is cast its valve-chest, C, whose axis is parallel with that of the cylinder. The inner ends of the cylinders and of the valve-chests open into the crank-case. The crank-case is closed at its forward end by the crank-case cover, D, a screw-plate of bronze, which takes the thrust of the

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forward end of the main shaft, E, which butts in a socket, F, cast in the center of the cover. The cover is prevented from jarring out by a locking-strip and screw, G, on its forward face. The after end of the crank-case, cast in one with the body, has an opening through the center with a short sleeve, H, which serves as a bearing for the main shaft abaft the crank. Forward of the crank is a round, or wheel, bearing of bronze, I, slipped on over the main shaft. The after bearings of the shafts are in the after end of the shaft-tube and in the tail-tube.

The main shaft, a hollow tube of bronze, carries the after propeller, whose pitch is left-handed, the forward propeller, right-handed, being carried by an outer tubular shaft of bronze surrounding the after end of the main shaft and geared to it by the gears in the gear-box, (G, Plates I and III) in the tail of the torpedo, the propellers thus being in tandem after the Ericsson system.

In each cylinder the piston, J, is packed by two bronze piston-rings. The connecting-rod, K, is attached to the inner side of the piston by a ball-and-socket joint, L. The socket, which is formed in a plug of aluminum-bronze, is screwed into the piston, and the ball-end of the connecting-rod is held in by a follower called the ball-joint cover, which screws into the plug and has a trunk space in which the connecting-rod plays. The inner end of the connecting-rod is secured to the socket of its crank-pin brass, M, by a screw-pin which carries a small pin drilled in its head at right angles to its length. This pin comes against a small safety-screw tapped in the crank-pin brass, preventing the screw-pin from being jarred out. Each crank-pin brass embraces the crank-pin through about 90° of arc and is held in place in an annular groove, N, cut in the end of each arm of the crank concentric with the crankpin, the ends of the brasses being finished with tongues

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to fit the grooves. A gate cut in the outer end of the forward arm of the crank permits sliding the brasses on or off the crank-pin, the gate being closed, when the brasses are in place, by a small removable brass piece, O, held by a screw. The screw securing the removable piece is accessible from the outside of the engine, in disassembling or assembling the crank-pin brasses, through a hole, P, in the crank-case, closed by a screw plug under the head of which a porpoise-hide washer is interposed. The crank is balanced by a counterpoise, Q, opposite each arm, forged in one body with the crank.

Air from the air-flask passes through air-pipes, by way of the reducing-valve in the valve-group, to an interior annular channel, R, cast in the periphery of the forward end of the crank-case and is conveyed from this annular channel to the outer end of each valve-chest by the air-passage, S, cast on the forward side of each valve-chest. The main valves, aaa, are piston valves, each of which, in its longitudinal motion in its valve-chest, travels over a port, b, connecting the outer end of the valve-chest with the outer end of its cylinder, successively admitting air over the valve to the cylinder, cutting it off, and opening the way under the valve for the exhaust from the cylinder to the crank-case and thence out through the hollow shaft. The valves receive their motion from the cam, c, keyed on the main shaft. The outer end of each valve-rod, d, ships in a socket in the inner end of the valve-stem, and the inner end of the valve-rod carries a roll, e, which bears on the cam with a constant push due to the air-pressure on the outer face of the valve. The valve-stems slide in circular guides, fff, which are attached to the valve-chest by ribs, the guides and ribs being cast in one with the valve-chests. The spaces between the ribs allow the passage of the exhaust air to the crank-case. The inner ends of the

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valve-rods slide in circular guides, ggg, cast in the ring-guide for valves which is secured inside the crank-case by screws, hhh, screwed in from the outside, a porpoise-hide washer being interposed under the head of each screw and each screw being kept from jarring out by a set-screw.

The cam for the valves is a disc cam of three principal curves. It is keyed to the main shaft and revolves with it under the valve-rod rolls and is held in place by the eccentric, i, for the counter, which screws on the main shaft against the forward face of the cam, to which it is fastened by a screw. The curves of the cam for the valves are such that air is admitted over the valve to any cylinder while its valve-rod roll is bearing against the curve nearest the center, cut off for expansion in the cylinder while the roll bears against the curve of intermediate distance from the center, and opened to the exhaust while the roll is lifted by the curve farthest from the center. The cut-off is at one-third of the stroke.

In the outer face of each main valve seats a relief valve, k, the stem of which loosely fits a socket in the end of the main valve. Fourteen radial holes through the head of the main valve open under the relief valve, affording a relief for air or water-cushioning on the outward stroke of the piston while the port is closed by the main valve. The relief valve is ordinarily kept seated, when not lifted by excessive cushioning, by the air-pressure on its outer face.

Holes, l, in the ends of the valve-chests permit the removal of the valves from the outside, through corresponding holes in the shell of the engine-room, for cleaning or changing. These holes are closed by screw plugs screwed in against porpoise-hide washers.

The engine oil-cup, of bronze, is on the starboard lower side of the engine-room and is secured to the after end of

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the engine-room cage by two holding-screws. It is filled through a copper pipe, accessible from outside the shell, attached to its after end. The outer end of this pipe, secured to the shell of the torpedo by two screws, is closed by a screw plug against a porpoise-hide washer. A small copper pipe connects the filling-pipe, to which it is attached beneath the screw plug, with the outer end of the air-passage of the starboard valve-chests, at m, and another small copper pipe, for feeding the oil to the engine, connects the forward end of the oil-cup with the socket in the crank-case cover, D, at n. This end of the pipe is finished with a flange which is secured by screws against a porpoise-hide washer. A small axial channel, shown by dotted lines in Plate VIII, is drilled in the main shaft, crank-arms and crank-pin. Connecting channels are drilled at right angles to this, opening from the crank-pin and from the main shaft at its bearings forward and abaft the crank. The oil is forced from the oil-cup through these channels by air-pressure from the valve-chest.

The valve-group combines in one casting the bodies of the reducing-valve, A, regulator, B, and valve-group oil-cup, C; the connections, D, for the air-pipe leading from the air-flask and E, for the air-pipe leading to the engine; the pivot supports for the starting-lever, F, and for the bell-crank, G; and the forward bearing of the counter-spindle, H. It is secured on top of the engine by a holding-screw attaching it to the after part of the engine body and by air-joint screws to the connections, D and E. Its removal through the engine-room door can be effected without disconnecting the after-body of the torpedo. It comprises the following principal parts:- the reducing-valve, A,

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with its controlling-valve, I; the regulator, B; the valve-group oil-cup, C; the starting-lever, F; the friction-cam, J; the friction-roll and worm-wheel, K; the bell-crank, G; the balance-lever, L; the distance-gear sector, M, with its adjusting-spindle, N; the counter-spindle, II, and worm, O; and the counter-ratchet, P. All parts are of bronze, except the bell-crank which is of nickel alloy.

A detailed description of the functions of these parts is given in following sections; their general object is as follows:-

The reducing-valve is for admitting air from the air-flask to the engine, the pressure of air admitted being governed by the position of the controlling-valve within the reducing-valve.

The regulator furnishes means for an adjustment by which the lift of the controlling-valve and the corresponding opening of the reducing-valve is proportioned to the pressure of air which it is desired to feed to the engine. The push of the regulator-spring is transmitted to the stem of the controlling-valve by the balance-lever.

The valve-group oil-cup contains a supply of oil for packing the stem of the controlling-valve.

The starting-lever automatically lifts the controlling-valve, when the torpedo is launched from the tube, admitting air to the reducing-valve, the motion of the starting-lever being transmitted to the controlling-valve through the friction-cam, the friction-roll, the bell-crank, and the balance-lever.

The distance-gear sector, set by the adjusting-spindle, provides means for automatically closing the reducing-valve and thus stopping the engine after the torpedo has traveled a predetermined distance through the water. The parts involved in this function are the counter-ratchet, the counter-spindle and worm, the friction-roll and worm-

The reducing-valve, A, is a piston valve with longitudinal vertical motion in its chest, which is fitted at its lower end with a seat for the valve and is closed, at the top by the cover, a, ground air-tight in its seat and held down by the follower, b, screwed over it. The reducing-valve is packed, in torpedoes of early manufacture, by two piston rings, which, in later torpedoes, have been omitted. Inside the reducing-valve works its controlling-valve, I, which is also a piston valve, the stem of which slides airtight in a sleeve cast in the lower end of the casting, the end of the stem projecting over one end of the balance-lever, L. A hole in the top of the reducing-valve, closed by a screw plug, which screws down against a porpoise-hide washer, permits removal of the controlling-valve for cleaning. The two, together, constitute a following-valve, the direction and scope of motion of the reducing-valve being the same as that of its controlling-valve.

Air enters the annular space, c, in the valve-chest, by the air-pipe, D, coming from the air-flask and, after having traversed the valve, passes to the engine by the air-pipe, E.

The working channels in the reducing-valve are the interior channels, d, e and f. These channels are in pairs, diametrically opposite, drilled in the valves in planes 120° apart, but they are shown in the plate as single channels in the same plane for the purpose of clearly illustrating the principle of the valve. Through d air has constant admission from c to the annular space between the two valve-faces of the controlling-valve, and thence it passes, when the controlling-valve is lifted, by the channel, e, to

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the annular space, g, under the head of the reducing-valve, lifting it from its seat, thus permitting air to pass to the engine; or, when the controlling-valve is lowered, by the channel, f, to the space, h, over the head of the reducing-valve, forcing it down, and thus throttling the engine. When the reducing-valve is lifting, as shown in Plate XI, the air from the space, h, over its head, exhausts through the channel, f, under the lower valve-face of the controlling-valve, to the small chamber, i, in the reducing-valve, and by leakage around the stem of the controlling-valve to the air-pipe, E. When the reducing-valve is lowering, the air from the space, g, under its head, exhausts through the channel, e, over the upper valve-face of the controlling-valve, and down through an axial hole in the controlling-valve and through openings connecting this axial hole
with the chamber, i, and then, by leakage around the
stem of the controlling-valve to the air-pipe, E. As the controlling-valve lifts or lowers, the reducing-valve takes up a corresponding motion until it reaches such a position that the channels, e and f, coincide with the two valve-faces of the controlling-valve, when the air is cut off from both the upper and lower sides of the reducing-valve and it comes to rest, in equilibrium. When the controlling-valve is completely down, the relative dimensions of the valves and their seats are such that the channel, f, is opened to the air-pressure and the channel, e, is opened to the exhaust and, consequently, the reducing-valve seats firmly, held down by the air-pressure above it, and cuts air off from the engine.

The unbalanced pressure of the air on the upper face of the collar, j, on the stem of the controlling-valve, constantly tends to force it down against the upward push of one end of the balance-lever, L, the other end of which is forced downward by the regulator-spring, k, It

22

is this pressure that seats the controlling-valve when the opposing push of the balance-lever is removed.

Within the body of the regulator, B, cast in one with the body of the valve-group, is the regulator-spring, k, held in a state of compression between the regulator-spring. barrel, l, in which the spring is dropped, and the regulator-plug, m, which bears on the upper end of the spring. The regulator-spring barrel slides loosely in the regulator body and projects from its lower end, bearing on the end of the balance-lever, L. A stop-collar, cast around the barrel, bringing up against a shoulder cast in the body, prevents the barrel from projecting downward unduly. The regulator-plug is a screw plug which may be screwed down, more or less, in the regulator body by a crank inserted in the square socket in its head from outside the shell of the torpedo.

The more the regulator-spring is compressed by screwing down the regulator-plug, the greater the push on the end of the balance-lever against which the regulator-spring barrel bears and the greater the force exerted by the other end of the balance-lever to lift the controlling-valve; consequently, the higher the lift of the reducing-valve and the greater the pressure of the air admitted to the engine. The number of turns to be given to the regulator-plug for two different speeds, the maximum of which the torpedo is capable at runs of four hundred and eight hundred yards, is given in the table of adjustments in the record sheet issued with each torpedo, the initial, or zero, point of the plug being that position in which its upper face is flush with the top of the regulator body.

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The balance-lever has rolls in its ends bearing under the regulator-spring barrel and under the controlling-valve stein. It is pivoted on the end of the lower arm of the bell-crank.

The valve-group oil-cup, C, is filled through an opening in the top, accessible from outside the shell of the torpedo, and is closed by a screw plug which screws in against a porpoise-hide washer. Air passes by an interior channel, drilled in the body of the valve-group, from below the seat of the reducing-valve to the bottom of the oil-cup whence it is conveyed to the top of the cup by an axial air-pipe forming a continuation of the interior channel. The pressure of the air on top of the oil forces it out through another interior channel connecting the oil-cup with two annular grooves in the sleeve, in the lower part of the casting in which works the stein of the controlling-valve, thus packing it air-tight.

The engine is started, on launching the torpedo, by the starting-lever, F, whose action on the controlling-valve is transmitted through the friction-cam, J, the friction-roll, K, the bell-crank, G, and the balance-lever, L.

The starting-lever is a bent lever, of bronze, whose upper arm projects through a longitudinal slot in the engine-room door and whose lower arm is pivoted in a socket cast
in the valve-group body. From the lower arm, on the face opposite the pivot, projects at right angles a pin, eccentric to the pivot, which carries the friction-cam. The bell-crank is pivoted at its elbow on a pin, cast in one

24

with the body of the valve-group, at the lower end of the regulator body. The upper arm of the bell-crank carries the friction-roll on a pin projecting at right angles from its inner face at the end of its lower arm is pivoted the balance-lever, the ends of which, fitted with rolls, hang under the regulator-spring barrel and the stem of the controlling-valve.

In the normal position of the starting-lever, before the torpedo is launched, the upper arm lies flat along the upper surface of the shell of the engine-room, the end of the arm pointing forward, as shown in Plates I and III. When the torpedo is launched the starting-lever catches under a tripping-latch in the tube and is thrown back, as shown in Plate X. As it swings back it carries the friction-cam to the rear against the friction-roll, swings the upper arm of the bell-crank aft, raises the lower arm of the bell-crank and with it the balance-lever which is thus pressed up against the regulator-spring barrel and the stem of the controlling-valve. The controlling-valve is therefore lifted and the reducing-valve is consequently opened for admission of air to the engine.

The operation of the distance-gear in automatically shutting off the air from the engine and thus stopping the torpedo at the end of a predetermined run is as follows:-

The counter-spindle, H, to which is attached at its forward end the counter-ratchet, P, is revolved by the engagement of the pawls, n, with the counter-ratchet, the pawls receiving reciprocating motion from the eccentric for the counter (i, Plates VIII and IX) on the main shaft. The worm, O, on the after end of the counter-

25

spindle engages the worm-wheel, K, mounted on a pivot on the inside face of the upper arm of the bell-crank, G, and communicates a motion of revolution to the worm-wheel and to the friction-roll, K, which is in one with the worm-wheel. While the engine is working, the starting-lever, F, is in its after position and, as has been described in the preceding section, the friction-cam, J, is carried to the rear against the friction-roll and is in firm contact with it, due to the pressure transmitted by the controlling-valve, I, and regulator-spring, (k, Plate XI,) through the balance-lever, L, and the bell-crank, G. Consequently, as the friction-roll revolves, it causes the friction-cam to revolve also. The friction-cam has a blank cut in its rim, as shown in the plate, and when this blank reaches the friction-roll the latter is forced forward in it, the upper arm of the bell-crank is no longer supported in its after position and the lower arm of the bell-crank, and with it the balance-lever, no longer exert a force tending to lift the controlling-valve. The latter therefore seats itself and the reducing-valve closes, shutting off air from the engine.

The distance-gear sector, M, set by the adjusting-spindle, N, provides means for making the adjustment by which the range of the torpedo is determined. The distance-gear sector is a thin disc of brass mounted on an axle formed by a shoulder on the outer face of the starting-lever, this shoulder being concentric with the pivot of the starting-lever. Around a portion of the periphery of the distance-gear sector are teeth which engage with a worm on the lower end of the adjusting-spindle. The adjusting-spindle is supported in a sleeve cast in one with the body of the valve-group. Its upper end is square and is accessible from the outside of the torpedo through a hole in the engine-room door. By

26

means of a socket-wrench, inserted through this hole, the adjusting-spindle can be turned to give any desired position to the distance-gear sector. On the outer face of the distance-gear sector is the stud, p, against which the pin, r, on the friction-cam is brought by the return-spring, s, when the adjustment for the range is made. The, farther the distance-gear sector is turned from right to left, as viewed in the plate, the farther will the friction-cam be revolved about its axle by the return-spring before the pin, r, brings up against the stud, p, and the farther will the blank space in the rim of the friction-cam be carried from the friction-roll; consequently, the longer will be the run of the torpedo after it is launched before the blank space will arrive, in the rotation of the friction-cam, at such a position as will allow the friction-roll to enter it.

A zero mark is established by turning the distance-gear sector, carrying with it the friction-cam through the contact of the pin, r, with the stud, p, until the recess in the cam comes to the position where the friction-roll is just ready to enter it, when the tooth of the sector opposite the pointer on the engine-room door is marked 0. The distance-gear is set for the desired run by bringing the zero to, the pointer and then turning the sector the number of teeth required, each turn of the adjusting-spindle moving the sector one tooth. Care must be taken that the pin, r, is carried by the return-spring against the stud, p, The number of teeth at which the sector must be set for runs of eight hundred yards and four hundred yards is given in the table of adjustments in the record sheet issued with each torpedo. The adjustments given in the table are for runs actually in excess of the two ranges and assure the completion of the run desired before air is shut off from the engine.

The object of this gear is to retard the admission of air to the engine from the instant of launching until the torpedo reaches the water, thus preventing undue racing of the engine. It consists of the following principal parts:- the retarding-lever, a; the bell-crank lever, b; and the water-tripper, c.

The retarding-lever, pivoted at d to an eye on top of the crank-case of the engine, with motion in a fore-and-aft direction, carries on its lower end a lug, e, which, when the retarding-lever is in its after position, projects over the forward end of the balance-lever, L, of the valve-group at such a height as to allow the balance-lever, when it is thrown up, to lift the controlling-valve, I, but a short distance, thus opening the reducing-valve only slightly. The upper end of the retarding-lever is forked and in the fork slips a pin projecting from the side of the lower arm of the bell-crank lever. The bell-crank lever is pivoted at f on the under side of the engine-room door, h, and to its upper arm, which projects through a slot in the engine-room door, is riveted the water-tripper, a thin plate of steel, shaped to conform with the curved surface of the engine-room door. Before the torpedo is launched the water-tripper is raised to its vertical position, as shown in the plate, swinging the lower arm of the bell-crank lever to the rear and moving the retarding-lever aft. When the torpedo enters the water, the rush of the water throws down the water-tripper flat on the surface of the engine-room door, swinging the lower arm of the bell-crank lever forward and moving the retarding-lever forward, withdrawing its lug from over the end of the balance-lever and,

28

consequently, allowing the latter to give its full lift to the controlling-valve, thus causing the reducing-valve to open for the full pressure for which the regulator adjustment has been made.

To retain the water-tripper in position, up or down, against light forces tending to displace it, the pivot of the bell-crank lever, supported in the spring-box, i, riveted to the under side of the engine-room door, is formed with an eccentric shoulder, filed flat on two sides, bearing on a spring-barrel forced upward by a spiral compression spring within the box.

In exercise, the water-tripper should always be raised when using tubes installed for over-water discharge, but never when using under-water tubes as not only is there no occasion for retarding the admission of air in the latter case, but the velocity of ejection may not be sufficient to cause the water-tripper to be thrown down.

The sinking-gear, used only in action, is for the purpose of automatically admitting water to .the after-body at the end of an unsuccessful run, thereby sinking the torpedo and removing it as a source of danger to friendly vessels, or preventing its falling into the hands of an enemy.

In the engine-bed plate, M, is the seat for the sinking-valve, j. A stem on the after side of the sinking-valve projects in the after compartment of the after-body and the valve, ground water-tight, is firmly held in its seat by the compression spring, k, encircling the stern between a nut on the after end of the stem and the after side of the sinking-valve seat. On the forward side of the sinking-

29

valve is an eye, n, in which is pinned the lower end of the sinking-lever, o, which is movable in a fore-and-aft direction, the fulcrum of this lever being a recess in the lower side of the sinking-lever block, p, which is supported by a clamp-screw, r, accessible from the outside of the torpedo, passing through a clamp-washer and a longitudinal slot in the engine-room door, h, To the upper part of the sinking-lever is pinned the sinking-lever hook, s. When the sinking-lever hook is disengaged from the pin, t, projecting from the outer face of the upper arm of the bell-crank, G, of the valve-group, and the sinking-lever is set in its after position by clamping the sinking-lever block at the after end of the slot in the engine-room door, the sinking-gear is inoperative; but, when the sinking-lever block is clamped at the forward end of the slot, and the sinking-lever hook is placed over the pin, t, the sinking-gear is in position to sink the torpedo at the end of the run; for, when the engine is automatically stopped, the upper arm of the bell-crank flies forward and carries with it the sinking-lever hook, swinging the lower arm of the sinking-lever forward and opening the sinking-valve, thus admitting water from the engine-room to the after compartment of the after-body.

In exercise, the sinking-lever and hook are taken out to prevent possible accidental sinking of the torpedo.

Although sinking-gear is provided for each torpedo, it is doubtful if its use is advisable as it is found, by actual experience, that the removal of one of the drain plugs in the after-body will accomplish the same result. Very little water will flow through the open drain hole while the torpedo is in motion but, when it stops at the end of the run, water will enter in sufficient quantity to sink it promptly.

The steering-engine (F, Plates I and III), situated on the port lower side of the engine-room, is secured to the engine bed-plate by two holding-screws. It is operated by air at the working pressure of the main engine and transmits the action of the immersion-mechanism, with increased power, to the rudder. It is wholly of bronze and consists of the following parts:- the cylinder, a, to which air is admitted from the outer end of the air-passage of the port upper valve-chest of the main engine by the pipe, b, and from which it is exhausted into the crankcase by the pipe, c; the piston, d, which has longitudinal fore-and-aft motion within the cylinder, due to air-pressure on either end; and the valve, e, which has longitudinal motion within the piston and, by its position, governs the relative position of the piston. The valve is connected to the lower connecting-rod and sleeve (l, Plate VI) of the system of levers of the immersion-mechanism by the valve-rod, f, the union, g, and the locking-jaws, m', The piston, virtually forming part of the steering-rod, s, is connected with the rudder by the union, r, the steering-rod, s, and a series of levers and connecting-rods in the tail of the torpedo (I, Plates I and III). The piston, d, and the valve, e, constitute, together, a following-valve. Every movement of the lower connecting-rod and sleeve (l, Plate VI), due to the combined action of the pendulum and hydrostatic piston, is transmitted in equal scope to the steering-engine valve and in equal scope, but with increased power, to the steering-engine piston and thence to the rudder.

The detailed action is as follows:- air at the working-pressure of the main engine has constant access from the

31

outer end of the air-passage of the port upper valve-chest of the main engine by the pipe, b, to the annular port, h, of the piston, and from this port it has constant access through the interior channel, i, to the annular space around the valve formed by the valve-faces, j and k. When the valve and piston occupy the relative positions shown in the plate the valve-faces, j and k, cover the interior channels, m and n, communicating respectively with the forward and after ends of the cylinder; air is cut off from both ends and the piston is, consequently, at rest. When the valve is moved forward by the action of the immersion-mechanism the valve-faces uncover the channels, m and n; air passes by the channel, n, to the after end of the piston, forcing it forward and putting the rudder up, the air from the forward end of the piston exhausting, meantime, through the channel, m, into the annular space between the valve-faces, j and l, and thence, by the interior channel, p, represented diagramatically by dotted lines, to the annular port, q, of the piston and out through the pipe, c, to the crank-case, whence it exhausts through the main shaft with the main engine exhaust. The movement of the piston in a forward direction continues until the channels, m and n, again coincide with the valve-faces, j and k, when the piston comes to rest. Similarly, when the valve is moved aft by the action of the immersion-mechanism, air is admitted by the interior channel, m, to the forward end of the piston, forcing it aft and putting the rudder down, the exhaust from the after end of the piston being by way of the interior channel, n, to the annular space between the valve-faces, k and e, and thence by the interior channel, p, to the port, q, of the piston and then by the pipe, c, to the crank-case and out through the main shaft.

The pipe, t, was formerly used for supplying oil for

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lubricating the steering-engine and packing the valve but its employment for this purpose is discontinued, sufficient oil entering with the air through the pipe, b. The pipe, t, is branched to the pipe, c, and takes no part in the working of the steering-engine.

Further details of the construction of the steering-engine are as follows:-

The piston is packed in the cylinder by bronze spring packings surrounding four ribs on the body of the piston. These packings are made additionally tight by air-pressure on their inner faces admitted by blind air-channels drilled in the faces of the ribs. A stem on the after end of the piston, to which is screwed the union, r, works through the stuffing-box, u, packed with a thimble-gasket of kid-leather, and a stern on the forward end of the piston works in the stuffing-box, v, in the cylinder-head, w. The cylinder-head screws in against a porpoise-hide washer, and the stuffing-box is packed with a thimble-gasket of kid-leather.

The valve fits snugly in the piston and has easy movement within it. An axial hole in the valve affords relief from cushioning, during movement of the valve aft, by oil or air imprisoned in the after end of the piston. The valve is packed by oil carried in annular grooves in the body of the piston-encircling the valve. To the forward end of the valve-rod, f, pinned to the valve at x, is screwed the union, g, which is secured to the locking-jaws, m', of the immersion-mechanism by a pointed screw, accessible from outside through a hole in the shell. A limiting-plug, y, screwed in the end of the forward stem of the piston, limits the travel of the valve in the piston.

Rigidly attached to the valve-rod, f, and forming part of it, is the valve-star, o, a star-wheel with six points, by

33

which the setting of the valve is adjusted. The forward end of the valve-rod screws in the union, g, with a right-handed screw-thread. Turning the valve-star to the right, or with the sun, looking toward the head of the torpedo, practically shortens the valve-rod, tending to put the rudder up, and turning it to the left practically lengthens it, tending to put the rudder down. The zero, or reference-point of this adjustment is that relative position of the valve within the cylinder which gives, when the valve is moved its full throw, a rudder movement of four divisions below the horizontal and three divisions above it, as indicated by a scale, divided in arc, on the port side of the after top-blade of the tail of the torpedo. The table of adjustments in the record sheet issued with each torpedo gives the amount by which the valve-rod should be lengthened or shortened from the zero point. A set-screw in the union, g, accessible from outside through a hole in the shell, prevents accidental change of this adjustment.

The union, r, connecting the piston with the steering-rod has longitudinal motion in a spring-box formed by enlarging the forward end of the steering-rod tube. The union is screwed on the after stem of the piston, and in the after end of the union screws the forward end of the steering-rod. A guide-screw in the spring-box enters a longitudinal slot in the union and keeps it from turning. The forward end of the steering-rod is encircled in the spring-box by a compression spring, z, one end of which bears against the after end of the union and the other end against the shoulder at the after end of the spring-box. When, at the end of the run of the torpedo, air is cut off from the engine and, consequently, from the steering-engine also, this spring forces the steering-rod forward, thus putting the rudder up, and bringing the torpedo quickly to the surface.

When the torpedo is launched the inertia of the pendulum causes it to lag to the rear, the effect of which, if unchecked, would be to put the rudder down and to give the torpedo a deep initial dive which, in shoal water, would endanger contact of the torpedo with the bottom. This lag of the pendulum continues during the acceleration of speed of the torpedo immediately after launching and until uniformity in speed is attained, when the pendulum recovers its plumb position and exercises its normal function. To prevent this deep initial dive, the locking- gear is provided by which the steering-engine valve-rod is locked in a desired fixed position until a sufficient time shall have elapsed to allow the pendulum to operate independently of its inertia, when the steering-engine valve-rod is automatically unlocked and the steering- engine comes under control of the immersion-mechanism.

The construction and operation of the locking-gear, made wholly of bronze, is as follows:-

It consists of the following principal parts:- the locking- jaws, m'; the locking-lever, c, and locking-lever spring, d; the releasing-lever, e, and releasing-lever spring, g; the ratchet-bar, h, and ratchet-bar spring, i; the stop-bar, k; the stop-screw, l; and the locking-star, p.

The locking-jaws, m', form the connection between the inner arm of the rock-shaft, m, of the immersion-mechanism, and the steering-engine valve-rod, f. (See also Plate VI.) The locking-lever, c, and releasing-lever, e, are pivoted to studs in the after face of the bulkhead of the immersion-chamber, the former at its middle point, r, and the latter at its outer end, s. The ratchet-bar, h, is pinned to the inner end of the releasing-lever and has longitudinal motion in the vertical plane through the guide, t,

35

secured by screws to the bulkhead. The stop-bar, k, pinned to the inner end of the releasing-lever and passing through a guide carried on the forward side of the inner end of the locking-lever, has at its lower end an eye, v, through which passes loosely the stop-screw, l. The stop-screw threads in the stop-screw nut, w, carried on the after side of the inner end of the locking-lever and has at either end a collar rigidly attached, one above the stop- screw nut and the other below the eye on the lower end of the stop-bar. The stop-screw has a square head on its lower end on which can be shipped a socket-wrench, inserted through a hole in the shell of the torpedo, for the purpose of adjusting the stop-screw higher or lower in the stop-screw nut when making the adjustment for locking the steering-engine valve-rod.

The ratchet-bar has thirteen saw-teeth cut on the inner side of its upper end which engage with teeth cut in the forward end of the counter-spindle, H, of the valve-group, a firm bearing of the ratchet-bar against the counter- spindle being maintained by the ratchet-bar spring.

The operation of the locking-gear is as follows:- to lock the valve-rod of the steering-engine, when making the locking adjustment before a run, the ratchet-bar is pushed down by a stiff rod inserted through a hole in the top of the shell of the torpedo, forcing down the inner end of the releasing-lever and with it the stop-bar, against the tension of the releasing-lever spring. As the stop-bar descends the eye on its lower end bears against the collar on the lower end of the stop-screw, pushing it down and, consequently, pulling down the inner end of the locking-lever between the locking-jaws, thus locking the steering-engine valve-rod against the action of the immersion-mechanism. The engagement of the teeth of the ratchet-bar with the teeth of the counter-spindle maintains the

36

locking-lever in position against the pull of the releasing-lever spring which tends to lift it.

The unlocking is effected automatically. When the torpedo is launched and the engine is in motion, the counter-spindle is revolved by the engagement of the pawls, n, with the counter-ratchet, P, the pawls receiving reciprocating motion from the eccentric for the counter (i, Plates VIII and IX) on the main shaft of the engine. The revolution of the counter-spindle permits the ratchet-bar to be raised tooth by tooth by the tension of the releasing-lever spring, the locking-lever spring holding the locking-lever, meanwhile, in engagement with the locking-jaws. When the smooth part of the ratchet-bar arrives at the end of the counter-spindle there is no further restraint on the action of the releasing-lever spring, the releasing-lever is consequently pulled up and with it the stop-bar, whose eye lifts the locking-lever clear of the locking-jaws, and the steering-engine valve-rod collies under the control of the immersion-mechanism.

When the ratchet-bar is pushed down its full length, thirteen teeth, as represented in the plate, the torpedo will run about one hundred yards before the steering-engine valve-rod is unlocked. By manipulating the stop-screw, 1, using a socket-wrench inserted through a hole in the bottom of the shell, the distance which the ratchet-bar can be pushed down may be regulated to any point between zero and the full number of teeth. The greater the number of teeth of the ratchet-bar engaged with the counter-spindle, counting from the lower end, the longer will be the interval of time after launching the torpedo before the locking-lever is released. This adjustment is given, for certain circumstances of practice, in the table of adjustments in the record sheet issued with each torpedo.

The locking-star, p, provides means by which the

37

steering-engine valve-rod may be locked in such a position as to maintain the rudder, during the period of locking, either horizontal, or slightly up, or slightly down, according to the circumstances of practice, so that the torpedo at the beginning of its run, before coming under control of the immersion-mechanism, may neither make too deep a dive nor come so near the surface as to endanger broaching.

The pivot of the locking-lever is a sleeve, r, slipped over a stud projecting from the after side of the bulkhead of the immersion-chamber. The after end of the sleeve has a short, rigid arm, x, projecting at right angles to its length, carrying the screw-threaded shank, z, of the locking-star, which is capable of revolution in the arm, but not of longitudinal motion. The screw-threaded shank of the locking-star engages a female thread tapped in the outer arm of the locking-lever. A spring stud in the outer end of the pivot stud of the locking-lever bears in shallow saucer-shaped holes in the forward side of the locking-star, preventing its displacement by jarring, but permitting its being turned by hand.

The action is as follows-the locking-lever being engaged with the locking-jaws, if the locking-star be turned to the right, looking toward the head of the torpedo, the locking-lever will be run aft along the shank of the locking-star, the locking-jaws, and with them the steering-engine valve-rod, will be moved aft and the valve of the steering-engine will consequently be in such a position as to cause the steering-engine to put the rudder down when air is admitted. If, on the contrary, the locking-star be turned to the left, the locking-lever will be run forward, moving the locking-jaws, the steering-engine valve-rod and the valve of the steering-engine forward, thus causing the steering-engine to, put the rudder up.

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The zero, or reference, point of this adjustment is that position of the locking-lever in its fore-and-aft movement along its pivot which will cause the rudder to be locked in the horizontal plane. The farther the locking-lever is moved aft from this position the more will the rudder be locked down; and, conversely, the farther the locking-lever is moved forward of the zero position, the more will the rudder be locked up. The locking-star adjustment, to be made when preparing the torpedo for a run, is given, for certain circumstances of practice, in the table of adjustments in the record sheet issued with each torpedo. A plus adjustment indicates that the locking-star is to be turned, from the zero position, the number of points directed to the right, or from the operator, locking the rudder down; a minus adjustment indicates that the locking-star is to be turned to the left, from the zero position, locking the rudder up.

The effect of locking is shown in Plate XVII, explained in the article describing the depth-register.

The tail of the torpedo (I, Plates I and III) is that portion abaft the after-body comprising the gear-box, G, of bronze, the tail-tube, a, of bronze, and the frame of the tail, of steel. The latter consists of the forward cone, b, and the after cone, c, each carrying, firmly attached to flanges on its outer surface, two pairs of flat blades, one pair on each in the vertical plane passing through the axis of the torpedo, and one pair in the horizontal plane. The blades are designated respectively as the forward and after top-blades, dd, the forward and after bottom-blades, ee, and the forward and after side-blades, ffff. The forward and after blades of each pair are joined stiffly together by rails,

39

hhhh, known as the top-rail, bottom-rail and side-rails. The top-rail carries on its upper edge a guide which, entering the guide-slot in the tube from which the torpedo is launched, insures accuracy of direction in launching.

The principal parts of the torpedo carried in the tail are the bevel-gears, in the gear-box, G, by which the motion of the main shaft is transmitted to the outer tubular shaft in a contrary direction; the propellers, UU; the rudder, R; the connections of the rudder with the steering-rod, S; and the vertical vanes, ii.

The gear-box, of bronze, is in two parts. The forward half is riveted and soldered in the rear end of the after-body and the rear half, prolonged in a tube designated the tail-tube, a, screws on the rear end of the forward half, after the gears are in place, and is kept from turning by two keys inserted in corresponding slots in either side of the two halves.

The bevel-gears, of bronze, are four in number: the forward gear, k, keyed on the main shaft and held in place by a nut screwed on the main shaft abaft the gear, the nut being kept from turning, after it is set up in place, by a screw pinning it to the gear; the intermediate gears, ll, which engage the forward gear and are carried loosely on the cross-head, m, the ends of which are squared on two faces and ship in the slots in the rear end of the forward half of the gear-box; and the after-gear, n, which is slipped on the main shaft abaft the intermediate gears and engages with them.

The forward gear is fitted with a male screw thread on its after face, on which is screwed time tool used to remove it in disassembling the tail.

The intermediate gears are carried on sleeve bouchings slipped over the ends of the cross-head, the bouchings being held in place by jam-nuts which are kept from

40

turning by split pins. The cross-head carries an axial sleeve through which passes the main shaft. In the top of this sleeve is the gear-box oil-cup, a bronze tube, the end of which is accessible from outside the shell, forward of the forward top-blade, and is closed by a screw plug under which is interposed a porpoise-hide washer. Oil is conveyed from the oil-cup by interior channels in the sleeve and in the cross-head to the bearing surfaces of the intermediate gears. Holes in the top and in the bottom of the gear-box admit water freely to the gears.

The after gear is cast in one with the outer tubular shaft, which is slipped on over the main shaft. A bronze friction-ring between the after gear and the axial sleeve of the cross-head, and three or more friction-rings between the rear face of the after gear and a shoulder in the forward end of the tail-tube maintain the after gear in position for true engagement with the intermediate gears. The main shaft has three bearings in the tail of the torpedo, one in the after end of the shaft-tube, E, and one at either end of the outer tubular shaft. The outer shaft has two bearings, one in each end of the tail-tube. The after-bearing oil-cup, accessible for filling from outside the shell, on the starboard side of the forward top-blade, is a bronze tube projecting from the upper side of the tail-tube, supplying oil to the after bearings through oil holes drilled in the outer shaft at the bearings.

The propellers, UU, of steel, are two-bladed with a pitch of thirty inches and of nearly equal blade area. They are carried in tandem, the forward propeller, right-handed, on the outer tubular shaft and the after, left-handed, on the main shaft. The hubs are conical and are bouched with bronze cones, pp, to each of which is secured its propeller with one key. The bodies of the cones are cut out to secure lightness and are slotted through length-

41

wise on one side for the purpose of giving a firm grip on the shafts when set up in place.

The cones slip on their respective shafts to which each is keyed with two keys on opposite sides of the shaft An interior shoulder on the after end of each cone butts against a shoulder on its shaft and assures proper longitudinal position of each propeller. Propeller-nuts, rr, of steel, screwed on the shafts abaft each propeller, force the propellers forward in place, causing the cones to bind the shafts firmly, thus securing a rigid grip free from rattling.

A tail-nut, t, of steel, screws on the tail-tube abaft the forward cone of the frame, holding the frame of the tail firmly in position.

When assembling the torpedo, the propellers, UU, propeller-nuts, rr, and tail-nut, t, are put in place in the frame of the tail and they are slipped together on the shafts. The tail-nut and propeller-nuts are then set up in succession until all parts are home, with the front end of the forward cone of the tail embracing the rear end of the gear-box, when each propeller-nut is secured by a setscrew let in between its forward face and the after face of its propeller.

The rudder, RR, of steel, is carried in the horizontal plane at the rear end of the tail, its forward edge barely clearing the rear edge of the after side-blades. It is in two parts, one on either side of the axial line of the torpedo, the outer ends of the two parts pivoted in bearings secured by screws to the after ends of the side-rails, the inner ends pivoted in the after-cone of the tail. The connections of the rudder, of steel, with the steering-rod, S, are the steering bell-crank, u, the forward connection, v, which has longitudinal motion in the vertical plane between guides on the rear edge of the forward bottom-blade; the balance connection, w, pivoted at its middle

42

to the bottom-rail; the after connection, x, which has longitudinal motion in the vertical plane between guides on the front edge of the after bottom-blade; and the tillers, zz. The connections are pinned snugly, end to end, to transmit the movements of the steering-rod to the rudder easily, but without lost motion.

The steering bell-crank is in two halves, right and left, on either side of the forward bottom-blade, to which it is pivoted at its elbow. Its upper arm is secured to the after end of the steering-rod by a pointed screw with a square head which can be put in place or removed by a socket-wrench inserted through a hole in the side of the shell. The upper end of the after connection is forked to pass clear of the main shaft, each fork being pinned to a tiller, one on each half of the rudder.

The movement of the rudder, up or down, is limited by a wedge, shaped on each side of the forward bottom-blade and forming one with it, in the interior angles of the steering bell-crank. On the port side of the after top-blade is a scale, graduated in arc, for use in connection with a pointer placed on the rudder when balancing the rudder. This scale has four divisions above and four below the zero mark, the zero indicating the horizontal position of the rudder. The eight divisions cover an arc of 15°.

The vertical vanes, ii, are small, stiff plates of steel, one on each forward side-blade of the tail, situated in planes parallel to the vertical plane passing through the axis of the torpedo. They are pivoted at their forward ends and can be swung on their pivots to starboard or to port to give a permanent rudder effect for the purpose of correcting any deflection to right or to left, in the run of the torpedo, due to eccentricity in the form of the shell. Each vane is made in two parts, one above and one

43

below the side-blade of the tail, the two parts, however, practically forming one, being secured together at the forward end by the screw which constitutes the pivot and, at the after end, by a clamp-screw which holds the vane firmly in place after it is set. The clamp-screws pass through slots in the forward side-blades of the tail. The rear ends of the vanes have pointers, referring to scales divided in arc, in eight divisions, marked on top of the forward side-blades of the tail, each division being equal to 1° of arc. The setting of the vertical vanes for individual torpedoes is given in the table of adjustments in the record sheet issued with each torpedo, a plus adjustment indicating that the starboard vane is to be set to the right the number of divisions directed, the port vane remaining at zero, and a minus adjustment, that the port vane is to be set in the position directed, with the starboard vane at zero.

The depth-register, of bronze, is an instrument which, screwed in the exercise-head of the torpedo, against a porpoise-hide washer, in place of the exercise-nose, automatically records the immersion of the torpedo at all points of the run, furnishing data for determining the efficiency of locking in checking the initial dive and for adjusting the length of the steering-engine valve-rod to give a uniform set depth during the run. In general terms, the depth-register consists of a tube with a conoidal head carrying a screw-fan which, revolved during the passage of the torpedo through the water, causes a ribbon of paper, wound on a drum, to be reeled on another drum, a pencil, attached to a hydrostatic pressure-gauge, marking a line on the paper, meanwhile, giving the depth-curve of the torpedo during its run. This curve is referred to

44

two coordinates, one, lengthwise of the ribbon of paper, in the direction of its travel from one drum to the other, corresponding to the distance run by the torpedo, and the other, at right angles, in the direction of the movement of the pencil, corresponding to the varying depth of immersion.

The detailed construction is as follows:- a tube, A, bearing the conoidal head, B, contains the piston, C, of the hydrostatic pressure-gauge which, on immersion of the torpedo, is forced aft against the tension of the spiral spring, D, by the pressure of water admitted through a hole in the head. On the after end of the tube, A, is shipped, with a bayonet joint, a base supporting two parallel drums, E and F, free to revolve around their axes. On the after face of the piston, C, is carried a flat spring pencil, G, of brass, which projects through a hole in the base supporting the drums and has longitudinal motion between the drums, in a line parallel to their axes, as the piston moves forward or aft. A tube, H, slipped over the tube, A, and free to revolve about it, is maintained in place by a shoulder in an extension-sleeve, I, which screws on the tube, A. The extension-sleeve also serves to carry the screw-fan forward, clear of the dead water in front of the head. On the after end of the tube, H, ships a tube, K, with a bayonet joint, practically forming one with it. The after end of the tube, K, carries a gear, L, rigidly attached, which engages with a gear, M, on the drum, F, and around the inner surface of the forward end of this tube is an internal gear which engages with the system of gears, N, P and RR. A two-bladed left-handed screw-fan, S, is carried by the conoidal head, its shank passing through an axial hole in the latter. As the torpedo passes through the water the revolution of the screw-fan is transmitted to the tubes, H, K, and consequently to the

45

drum, F, by the gear, N, on the shank of the screw-fan, the gear and pinion, P, the compound spindle-gear, RR, and the internal gear in the end of the tube, H. On the drums are clamps, TT, for securing the ends of a ribbon of prepared paper which, wound on the drum, E, is reeled up on the drum, F, during its revolution. The drum, E, is stiffened by a spiral friction-spring, U. The paper passes under the after end of the pencil, G, which traces on it the depth-curve for the run.

Three depth-curves, taken from cards obtained in practice, under the same conditions of launching, are represented in Plate XVII, Figs. 1, 2 and 3. The relations of the moving parts of the depth-register from which these cards were obtained are such that the ratio of the scale showing the immersion to the scale showing the distance run is, approximately, one to twenty. Figs. 1a, 2a and 3a show the depth-curves projected on a uniform scale. They illustrate the effect of locking. In Fig. 1, the torpedo was launched unlocked. The deep initial dive and subsequent irregularities of immersion are apparent. In Fig. 2, the locking-gear was locked about one-half the length of the ratchet-bar, with the rudder very slightly up. The undue initial dive was overcome, the torpedo went almost directly to its set depth and ran uniformly in the horizontal plane. In Fig. 3, with the locking-gear locked about one-half the length of the ratchet-bar and the rudder too far up, the torpedo came to the surface, along which it ran until the locking-lever was released, when the immersion-mechanism gradually steered the torpedo to its set depth.

The rolling-register, of bronze, is an instrument which, screwed in the exercise-head of the torpedo, in place of

46

the exercise-nose, automatically records the rolling of the torpedo to starboard or to port during its run. It consists of a tube with a conoidal head carrying a screw-fan which, revolved during the passage of the torpedo through the water, causes a bar pendulum to be run aft within the tube along a screw-threaded shaft carried axially within the tube. A flat spring pencil, of brass, secured to the tube and bearing on a strip of paper attached to the under side of the pendulum traces a line, meanwhile, which corresponds with the central longitudinal line on the bottom of the pendulum, if there be no rolling, but which curves to right or to left of this line if the torpedo rolls in either direction.

The detailed construction is as follows:- a tube, a, bears the conoidal head, b, which carries the two-bladed, right-handed screw-fan, c, whose shank passes through the head and engages, by gearing, with the shaft, d, which is carried axially in the tube, its after end being supported in a socket-bearing in the cap, e, shipped on the after end of the tube with a bayonet joint. A bar pendulum, f, free to swing in the transverse vertical plane passing through the axis of the torpedo, is suspended from two supports, gg, which are rigidly connected to a sleeve, h, encircling the shaft, d. These supports are maintained upright in the vertical plane by a guide-slot in the upper side of the tube, a, in which their upper ends enter. The sleeve, h, carries on its upper side a sectional-nut, i, which engages with a screw-thread cut on the shaft, d. The sectional-nut is borne on the after end of an arm, pivoted at k, the forward end of which is tapered to a flat spring resting on the upper side of the sleeve, the spring tending to keep the sectional-nut engaged with the thread on the shaft. The sectional-nut may be lifted clear of the thread on the shaft, permitting removal of the pendulum for

47

preparation or examination, or dropped into engagement with the thread in position for action during the run of the torpedo, by the double tilting-lever, l. This lever consists of a collar encircling the arm of the sectional-nut abaft its pivot, carrying two short transverse arms, accessible through holes in the tube, a. On the inner side of the collar is an eccentric shoulder which bears on the upper surface of the sleeve, h. Tilting down the starboard arm engages the sectional-nut with the thread of the shaft and tilting down the port arm releases it In the bottom of the tube, a, is secured a spring pencil, m, of brass, the forward end of which presses on the bottom of the pendulum. An extension-sleeve, n, on the tube serves to carry the screw-fan forward, clear of the dead water in front of the head.

To prepare the rolling-register for use, a strip of prepared paper is stretched flat on the under side of the pendulum to which it is secured by clamps at either end; or, if it is not desired to preserve the record of rolling, the bottom of the pendulum may be lamp-blacked. The pendulum is then slipped in place at the forward end of the tube, with the head of an arrow stamped on the sleeve, h, pointing forward. The cap, e, is shipped on the after end of the tube, the sectional-nut is engaged with the screw-thread on the shaft and the rolling-register is screwed in the exercise-head, care being taken that the pendulum hangs in the vertical plane passing through the axis of the torpedo. This adjustment in the vertical plane is effected by the adjusting-collar, p, and the extension-sleeve, n. The adjusting-collar screws firmly in the forward end of the tube, a, taking up more or less, as required in assembling the parts, against a porpoise-hide washer, r. When the rolling-register is screwed in the head of the torpedo the nearest one of the longitudinal

48

lines cut around the extension-sleeve is brought in coincidence with the line marked on the upper side of the forward end of the head and the adjusting-collar is then turned by a spanner until the line cut on its upper side coincides with the line on the forward end of the head and the corresponding line on the extension-sleeve.

After the rolling-register is properly secured in place, a few preliminary turns are given to the screw-fan, by hand, to trace a short initial line to which may be referred the subsequent curve traced automatically during the run of the torpedo.

[APPENDIX A.]

MODIFICATIONS OF
The Whitehead Torpedo.

U. S. NAVY, 3.55m. X 45c/m., MARK II

This torpedo differs from the Mark I as follows:-

I. RETARDING- LEVER.

This is pivoted between two arms cast on the lower end of the cylinder which contains the controlling and reducing-valves, and a small roller is fitted to the end of the bell-crank of the water-tripper to work in the slot of the upper end of the retarding-lever, thereby reducing friction.

The retarding-lever itself is larger than the Mark I.

II. REGULATOR-SPRING.

This spring is not completely relieved from compression until the plug is backed out two and one-half turns above the zero position; so when the plug is at zero there is only a compression of two and one-half turns of the regulator-spring, although no account is taken of it.

III. AIR-PIPE JACKET.

The air-pipe is surrounded by a tubular water-tight jacket extending from the after bulkhead of the immersion-chamber, forward for a distance of about six inches. This tube is about one quarter of an inch greater in diameter than the air-pipe which passes through it. The pipe is free in the jacket except at its forward end where the jacket is joined to it, thus giving more play to the pipe

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for making connection with the air-pipe leading to the valve-group.

IV. BUOYANCY.

The weight of the war-head, complete, including war-nose and dry primer, is 180 lbs. 10 oz.; that of the exercise-head, complete, including exercise-nose, 177 lbs. With the air-flask charged to 1350 lbs. per square inch, the torpedo, completely ready for launching, weighs in the war-condition, 840 lbs. 10 oz.; in the exercise condition, 837 lbs. In the exercise condition there is a slight initial buoyancy of 1 lb. These are average weights. Owing to variations in the weights of the air-flask and tail sections there may be no initial buoyancy, even in the exercise condition.

V. VALVE-GROUP.

The holding screws and air-joint screws are of different size from the Mark I.

VI. STOP-VALVE.

The operating-spindle is made of steel. The lower section of the spindle (below the collar) is longer than the Mark I and the upper section is smaller.

VII. CHARGING- VALVE SEAT.

The seat is larger than in the Mark I, requiring a larger washer (No. 8). A bouching is provided for the charging-valve plug and seat; the bouching is held in place by a set-screw.

VIII. SIDE-HOLES.

There are no side-holes for working off the after-body as in Mark I.

IX. VALVE-STAR.

The valve-star screws into the valve-rod union with a left-hand thread so that turning it to the left looking

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towards the head, shortens the valve-rod; the valve-rod on which the star is mounted is longer than the Mark I.

X. STEERING-ENGINE.

This is one inch shorter than the Mark I. The oil-pipe connection formerly used in Mark I, is omitted. The piston has but three ribs, each packed with two bronze rings.

XI. STEERING-ROD.

If the after-body is off, the length of the steering-rod can be altered most conveniently at the forward end instead of taking off the tail. The steering-rod tube is of greater diameter than the Mark I, thus allowing the bulge on the after end of the steering-rod to pass through it. The forward end of the tube passes through the ("E") washer, thus requiring a larger hole in the washer than the Mark I.

This consists of a bell-crank pivoted to the bulkhead immediately under the hydrostatic-piston, one arm of which is vertical and the other horizontal, and a yoke with a collar at its upper end. The lower end of this yoke pivots at the end of the horizontal (lower) arm of the bell-crank and is large enough to pass around and clear of the hydrostatic-piston tube, the two arms of the yoke meeting in a collar which works loosely around the socket-post below the adjusting-nut. The vertical arm of the bell-crank has a ball at its upper end which works in a socket in the under side of the hydrostatic-piston. The action of this mechanism is as follows: turning the operating-spindle of the depth-index to the

52

left, causes the adjusting-nut to push the collar down, thus pushing down the horizontal arm of the bell-crank and causing the vertical arm to pull the piston forward, the compression of the spring of the hydrostatic-piston being diminished by the action of the hydrostatic-piston bell-crank at the same time. In balancing the throw of the rudder due to the hydrostatic-piston, the piston is in, when the 5 ft. mark on the depth-index is at 8 o'clock the piston is out when the 5 ft. mark is on the fore-and-aft mark on the shell of the torpedo.

The nuts for the screws of the holding-ring of the rubber diaphragm are of different size from the Mark I.

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[APPENDIX B.]

MODIFICATIONS OF
The Whitehead Torpedo.

U. S. NAVY, 3.55m. X 45c/m., MARK III, AND
5m. x 45c/m., MARK I.

The 3.55m. X 45c/m., Mark III, and the 5m. X 45c/m., Mark I, torpedoes differ from previous Marks in the following particulars:-

These two new Marks are identical, or similar, in all the details of mechanism and manipulation, except that the 5m. X 45c/m., Mark I, has a new rudder-index and scale. This index is a small pointed arm that clamps by a set-screw to the after edge of the port horizontal rudder near the extremity of the shaft. The scale is a composition casting, fitted to slip over the end of the shaft and to be held rigidly by a slot embracing the edge of the after top-blade. On the left face next the pointer is a graduated scale by which the rudder throw in points may be noted.

The Obry steering-device, consists essentially of the gyroscope, F, G, H, (wheel and two gimbal-rings); the

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impulse-sector, I; the impulse-spring, K; the cam-shaft, L; the air-cushion cylinder, D; the valve-mechanism, B, b, c; the steering-engine, C; and the frame, A. The minor parts are the horizontal rock-shaft, P; the position-holder, U; the vertical rock-shaft, V; the centering-stud, w; and the rock-shaft spring, Y. The relative movement between the axes of the torpedo and the gyroscope wheel when running, operates the valve of the steering-engine, giving motion to a steering-rod. The steering-rod by suitable mechanism operates a pair of vertical rudders by which the horizontal-direction errors of the torpedo are controlled.

THE GYROSCOPE.

The gyroscope wheel is of Tobin bronze, and of compact pattern, somewhat enlarged near its periphery for proper distribution of its mass. Its diameter is 3 1/8 inches, and weight 1 3/4 lbs. The axle is 2 7/8 inches long and tapers toward its extremities. In the ends of the axle are inserted hard steel bearings, coned to receive the pivots upon which the wheel turns. Near one extremity the axle is toothed to correspond with the teeth of the impulse-sector by which it is actuated. The wheel is drop-forged and finished in the lathe centered on its steel bearings.

The inner ring is of Tobin bronze, drop-forged and carefully machine-finished. At the extremities of one diameter of the ring, cone-shaped steel pivots are inserted upon which the wheel turns. The pivots, qq', are secured to the ring by the threaded portion and thereby are adjustable to the bearings of the wheel. The ring is split through the holes tapped for the pivots and thus the latter may be securely fixed after adjustment, by set-screws, rr, binding the split portions together. At points on the

55

outer surface of the ring, 90° from the pivots, are fitted steel bearings, pp, by which it is supported and may revolve upon the pivots, nn, of the outer ring. A portion of the inner ring near one pivot is slotted away to avoid interference with the impulse-sector, in its engagement with the toothed axle of the wheel. The outer end of the pivot that carries the toothed end of the axle is coned out to afford entrance of the centering-stud, w, by which the wheel is held true during the application of impulse by the sector.

The outer ring is also fitted with pivots, nn, and bearings, mm. The pivots are adapted to the bearings of the inner ring, and are adjustable. The bearings of the outer ring permit the gyroscope as a whole to revolve about a vertical axis, the pivots, kk, being adjustable and secured in the frame by the clamping-screws, ll. The bearings of the outer ring carry no steel bouchings, as they sustain but little lateral strain. Secured to the outer ring in a vertical position, is the control-pin, a, by which the valve-arm is actuated admitting air to the steering-engine, C.

In the design of the wheel and rings careful attention is given to the balancing of weights on opposite sides of the axial planes, but symmetry of form is sacrificed to some extent for practical reasons.

THE IMPULSE-SECTOR.

The impulse-sector is of Tobin bronze, machine-finished. It consists of a substantial hollow shaft 3 inches long and 1 1/8 inches external diameter. From its upper extremity a broad conical-shaped flange spreads outward and downward, upon the lower edge of which teeth are cut for engagement with the axle of the gyroscope wheel. The radius of the toothed sector is 2 3/16 inches, and it comprises 276° of arc. The remaining portion is entirely cut away

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leaving space for the free operation of the gyroscope without interference after the impulse has been given.

The boss, M, is a small projection on the impulse-sector, which by its operation on the boss-arm, X, of the vertical rock-shaft, V, withdraws the centering-stud from the gyroscope wheel immediately after impulse is given.

The stop, N, is a small thick steel plate screwed to the upper surface of the sector. In connection with the stop-arm, O, and the air-cushion piston, it limits in both directions the rotation of the impulse-sector upon its axis.

The stop-arm, O, is a simple steel link, having an eye at one end by which it turns freely around the upper extremity of the cam-shaft, L, and the other end is fitted to work in the slot of the air-cushion piston. By rotation of the impulse-sector about its axis (using the winding-key, or under the action of the spring) the stop finally bears against and moves the stop-arm, which in turn drives the piston toward one end or the other of the air-cushion cylinder, according to the direction of the rotation.

The cam-shaft, L, is a stiff bronze rod inserted axially in the hollow shaft of the impulse-sector. It has the cam, y, at its lower end, and a square section near its upper end, fitting a corresponding orifice in the top of the sector. A socket of square section in the cam end permits the insertion of the winding-key by which the necessary tension is given to the spring and the sector turned into position for giving the impulse.

THE IMPULSE-SPRING.

The impulse-spring, K, is a helicoid of 18 turns of No. 8 wire (B. W. G.) wound on a cylinder 1 5/16 inches diameter, and 3 1/8 inches long. The ends of the wire are hooked outward to embrace the driving-studs, one of which is in the bottom of the frame, and the other in the impulse-

57

sector. When the cam is released by tripping the cocking-toe, R, the torsional effort of the spring on the studs causes the impulse-sector to revolve upon its axis, until arrested by the stop-arm, and to transmit rapid rotation to the wheel of the gyroscope.

THE AIR-CUSHION CYLINDER.

The body of the air-cushion cylinder, D, is a continuation of the cylinder of the Obry steering-engine, C, and is cast in one mass with the frame, A. It is open at the outer end, but closed at the cushion end by a thick diaphragm separating it from the Obry steering-engine. The piston is a stout plunger fitted to work nicely in the cylinder, being sufficiently air-tight without packing-rings. Its middle portion is partially cut away, and both the cylinder and the piston are slotted for the action of the stop-arm.

Air is drawn from the reducing-valve of the valve-group at the running pressure of the main engines, and carried by piping through the engine-room bulkhead to the starboard pedestal of the door-jamb in the after-body, whence it is further conveyed through the air-tight joint and fixed piping, h, to the valve-body, B. In its passage through the engine-room the air pressure is further lowered by the small reducing-valve, (Plate XXIV), to about 150300 pounds.

In Fig. 1, B, is the valve-body; c, the valve-plug; a', the valve. Air is supplied by the channel, o', to the annular groove, f', around the valve-plug from which it passes through the channels, b'b', (see middle section) to

58

an annular groove, c', around the valve. Two longitudinal surface channels, d'd', on the valve carry the air both upward and downward to the top and bottom sections, where it is arrested and awaits further movement to be determined by the operation of the valve.

The Figures marked "top" "middle" and "bottom" sections, respectively, are sections through the annular grooves of the valve-plug shown in the vertical section, Fig. 1, at e', f', and g', In each view, the valve is shown in its neutral position. The operative faces and ports are so constructed that any appreciable movement of rotation of the valve will admit and exhaust air through the appropriate ports.

If the valve be turned slightly in a right-hand direction, air will pass (see top section) from the longitudinal channels, d'd', to the ports, h'h' of the valve-plug, then to the annular groove, e', of the valve-plug from which it has access by the channel, i', to the forward end of the steering-engine, driving the piston aft, and putting the rudder to port. Coincident with this movement, exhaust air leaves the after end of the steering-engine through the channel, k', passes into the annular groove, g', (see bottom section), thence through the ports, l'l', of the valve-plug into the exhaust ports, m'm', of the valve, whence it emerges through a central longitudinal orifice, n', in the valve, exhausting directly into the after-body of the torpedo.

The valve-body B, (Plate XXV, Fig. 1), is reamed to form a conical shaped cavity into which the valve-plug fits practically air-tight without packing. The supply air-channel, o', leads to the surface of the cavity near its middle portion where it communicates with the annular groove, f', of the valve-plug.

The valve-plug, c, is coned to fit the recess of the valve-

59

body. It is of rectangular shape at the top, and provided with holes through which pass the valve-body studs, by which the valve-plug is kept seated. The valve-plug has an axial cylindrical hole in which fits, with great nicety, the valve, a', working practically air-tight without packing. Three annular grooves, e'f'g', are cut around the body of the valve-plug. Air is received at the middle groove, and supplied to and exhausted from the engine through the upper and lower ones. Radial holes communicate from each annular groove to the axial hole, where they meet the corresponding valve-faces and passages. (For convenience of manufacture the valve-plug is made in two parts, an inner sleeve being drifted in axially, after working the air-passages through it from its outer surface. For all theoretical or practical purposes connected with the working of the valve-plug, it may be regarded as of one piece).

The valve, a', is a plain cylinder having an axial hole through its entire length. The lower portion is fitted for the valve action, and the upper portion constitutes a stern for the application of the valve-arm, b, (Plate XXV, Fig. 2). Near the middle of the portion fitted for valve action, on the exterior surface is an annular groove, and from this annular groove, two longitudinal surface channels, both upward and downward, are cut for a distance reaching to the upper and lower channels of the valve-plug. Near the extremities of these longitudinal surface channels are also radial holes constituting the ports leading exhaust air to the axial hole. A small radial hole near the upper end of the valve is for the insertion of a pin, in the manipulation necessary to adjustment.

The valve-arm, b, (Plate XXV, Fig. 2), is a steel piece of rectangular section at the upper end, and fitted with two holes, through one of which the upper end of the valve

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passes, and through the other a set-screw by which the two pieces are held together. The metal is then thinned and bent downward, and fashioned at its lower end to the form of a yoke that embraces the control-pin, a, when the parts are assembled for action. At the middle of the yoke a small slot is cut in which the control-pin works to operate the valve. When by the mutual action of the control-pin and the valve-arm, the limit of useful valve motion has been given, the control-pin passes out of the slot, and the horns of the yoke being curved to the same arc upon which the control-pin travels, no further valve motion ensues until by return action the horn of the yoke has guided the control-pin into the slot.

The valve-guard, g, (Plate XX), is a small piece of sheet brass bent to conform in shape to the valve-arm. In its upper portion are two holes through which the valve-body studs pass. It is held in place just clearing the top of the valve, by the stud-nuts. In adjusting it to this position, it bears upon the valve-plug springs, ee, previously dropped over the studs. A small hole, directly over the axial hole of the valve permits free exhaust. The office of the valve-guard is to keep the valve-plug seated, prevent the valve from rising out of place, and to protect the valve-arm from injury in handling.

TO ASSEMBLE THE VALVE-MECHANISM.

This should be done with the instrument in the adjusting-stand. The valve-plug is entered in the valve-body and adjusted to its approximate mid position by the valve-plug adjusting-screws. Place the valve-plug springs in position. Pass the valve through the valve-arm to its approximate position, and enter it in the valve-plug without clamping the arm to the valve. The yoke of the valve-arm should be in position embracing the control-

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pin, and the latter should be held in its true gyroscopic position by the centering-stud and position-holder. The gyroscope wheel need not be running. Put on the valve-guard and seat it with time stud-nuts. Pin the bar of the adjusting-stand central, and see that the valve-arm clamp-screw is slack. Now admit air and roll the valve by a pin through the pin-hole in the side of the valve under the valve-arm, until the mid point is found from which the Obry engine works freely both ways. This is the closest adjustment that can be made with the valve itself. Clamp the arm to the valve. (The clamp-screw, b", will make an indent in the valve, and this indent will be a guide in subsequent adjustments of this kind, should they become necessary). More refined adjustment when shown to be necessary from actual runs of the torpedo is made by the valve-plug adjusting-screws, which turn the valve-plug slightly in its seat.

The Obry steering-engine, C, is a simple cylinder of 5/8 inch diameter, and 9/16 inch stroke. The piston, p', is 2/3 3/2 inch in length and fits practically air-tight without packing. The piston-rod, q', is fitted with a flange, i, at one end by which it is firmly held by the steering-rod coupling, j, and a smaller flange at the other end connects it with the piston.

The frame, A, is an irregular shaped casting upon which are mounted and assembled the gyroscope and the impulse-sector, together with the accessory parts involved in their operation. The valve-body, B, the Obry steering-

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engine, C, and the air-cushion cylinder, D, are cast as parts of the frame. Two stout lugs, EE, are provided for securing the frame to the pedestals of the door-jamb, and smaller lugs provide bearings for the light rock-shafts and accessories.

The horizontal rock-shaft, P, carries at one end the position-arm, Q, that operates the position-holder, U. Near the middle is the cocking-toe, R, which engages with the cam, y, holding the impulse-sector at cock after winding. At the other end is the trigger, S, against which the lower arm of the releasing-lever, (r's', Plate XXVI) presses when the torpedo is launched, withdrawing the cocking-toe, R, and releasing the cam, y, thus permitting the impulse to be given.

The position-holder, U, is a small piece of sheet brass fashioned at one end as a clutch, to partially embrace the two gimbal-rings and thus hold the gyroscope in proper position for receiving the impulse. It is pivoted at the other end to the frame, and receives its motion from the position-arm, Q, through the medium of a stiff wire link, T.

The vertical rock-shaft, V, carries at one end the stiff centering-arm, W, fitted at its extremity with the centering-stud, w. The stud is shaped to enter a conical recess in the steel center that carries the forward end of the axle of the gyroscope wheel. The purpose of the

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centering-stud is to accurately center and support the wheel of the gyroscope while it is receiving the impulse,; the holding-clutch, U, not being adequate to this purpose, and designed only to put the instrument in approximate position for the centering-stud to act, and to steady and support the rings.

A boss, M, on the impulse-sector acting upon the boss-arm, X, of the vertical rock-shaft, removes the centering-stud from the axle of the wheel as soon as the impulse has been given, and withholds it until the impulse-sector is re-wound.

The position-holder, U, and the centering-stud, w, tend at all times to hold and center the gyroscope by the constant action of the rock-shaft spring, Y, pressing against the centering-arm, W, and the trigger, S, of the two rockshafts. It is only when the effort of the spring is overcome by the stronger efforts of the lower arm of the releasing-lever, and of the boss, M, on the impulse-sector, that the gyroscope is left to its own action free from restraint. In the operation of winding, the position-holder, U, momentarily drops from the rings, by the action of the cam, y, upon the cocking-toe, R, but when the sector is fully wound and cocked the position-holder resumes its function.

OBRY GEAR ADJUSTMENTS.

There are practically two kinds of adjustments to consider in the use of the Obry gear, viz:- gyroscope adjustment, and valve adjustment.

1. Gyroscope adjustment. In considering these adjustments (usually made on the adjusting-stand) it is convenient

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to regard the instrument as in its, normal running position in the torpedo, and for the operator to conduct his work or experiments from an assumed point above and abaft the instrument. He may then, looking downward, observe the movements on the horizontal plane, or, looking in the direction the torpedo is supposed to be running he may observe the after face of the gyroscope wheel and rings. Plate XXIII represents such a view of the gyroscope. When in operation, the wheel turns in the direction indicated by the arrow.

The following general gyroscope movements are readily observed by simple experiment on the adjusting-stand. There is no necessity for attempting to memorize them.

When the wheel is revolving if we press downward upon the inner ring near q, the entire system will turn about the vertical axis, mm', (for m see Plate XXII, m' not shown in the figure) in the direction nqn'. Again, if the counter-weight at q is moved aft, that is, further from the center of the system, it is equivalent to additional weight or increased downward pressure at q, and the same horizontal movement nqn' is observed.

Similarly, if the wheel itself be moved bodily aft by slacking off the screw-pivot at q, and setting up correspondingly on the pivot at q' the operation is equivalent to increased downward pressure at q and we have the same resulting movement in the direction nqn' Reversing the character of any of these experiments or adjustments will give opposite movement about the vertical axis in the direction nqn'. If the gyroscope is in perfect adjustment when impulse is given it will have no movement about either axis mm' or nn', and when the torpedo is running, the valve-arm will be moved by the control-pin only by the changes of direction in the torpedo itself which changes of direction are self-corrective by design.

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If, however, the gyroscope is out of adjustment and has movement about the vertical axis mm' in either direction, the control-pin, a, will tend continually to press the valve-arm in one direction, and although changes of helm will be made as usual, preponderance will be toward one side and the torpedo will have resultant helm in one direction producing a curved trajectory in the horizontal plane. It may be noted here that if the gyroscope has right-hand motion, nq'n'q, the torpedo will describe a curve of right-hand motion q'rs; and conversely, (see marginal figure). The gyroscope-fault indicated by figure would be corrected by moving the counter-weight outward toward the end of its stem, or by moving the wheel bodily aft by slacking at q and setting up at q'. Decided errors are usually corrected by moving the wheel; later and more refined adjustments are made by the counterweight.

When the adjustments have removed all horizontal rotation about the vertical axis mm', it will generally be found that vertical rotation about the horizontal axis, nn', has also been much reduced if not altogether removed.

Some movement about the axis, nn', may be permitted

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without the steering qualities being affected. Extreme cases may be improved by adjustment of the pivots and centers at n and n'.

In the adjustment of pivots to their bearings the pivots should be' set up just enough to remove all axial motion, but not to jam or bind.

2. Valve adjustment. If the gyroscope adjustment is perfect, the control-pin will remain motionless, and all valve movement will be due to the deviations and changes of direction in the torpedo itself. A very slight deviation of the torpedo from its course (about 1 1/2°) will admit air to the engine, putting the rudder hard over in the sense that corrects the deviation. The rudder remains over and produces over-correction until the deviation on the opposite side is sufficient to reverse the valve effect, and thereby reverse the rudder. The rudder is thus hard over alternately starboard and port, as from the critical design and construction of the valve-ports it cannot remain any appreciable time in the neutral position. The torpedo thus makes a sinuous path in its run, deviating an equal amount on either side of a middle line which becomes its resultant course.

This resultant course, although a straight line, may not be in the direction of the line of sight. This is because of the small dimensions of the valve-ports and air-passages, and the difficulties of exact workmanship on the small cylindrical surfaces. It thus happens that in the assemblage of valve-plug, valve, valve-arm, and control-pin, the valve may not be in the exact neutral position with reference to the admission ports when the wheel is centered for the impulse. When the torpedo is launched and assumes its own control, it finds a resultant course due to the exact working neutral position of the valve.

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Figure in margin shows the error (exaggerated) in the torpedo's course due to this cause. The valve is adjusted and the error corrected by turning slightly the valve-plug by means of its adjusting screws. Turning the valve-plug in a right-hand direction (arrow at a) will cause the course of the torpedo to diverge to the right as shown in the figure while turning it in a left-hand direction (arrow at b) will cause it to diverge to the left. To correct the error of the run shown in the figure, the valve-plug should be turned in the direction of the arrow b. This is done by slacking screw d, and setting up on d'.

The releasing-mechanism of the Obry gear takes its initial action from the upper arm of the bell-crank on the valve-group. (Plate XXVI, t'.)

When the starting-lever is thrown back in the operation of launching, the upper arm of the bell-crank moves aft. To this arm is pinned a. short link, u', the other end of which is pinned to the forward end of the push-rod, v', The push-rod passes through the stuffing-box, v",

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of the engine-room bulkhead, and its after end presses against the upper arm, w', of the releasing-lever, s', The releasing-lever, s', is a vertical rod in the forward part of the after-body, pivoting in brackets and operating as a rock-shaft. It has an upper and a lower arm of about equal length. When the push-rod, v', bears against the upper arm, w', the lower arm, r', carrying the adjustable-head, x', presses against the trigger, S, of the Obry gear, releasing the cam, y, and permitting the impulse-spring to give its action.

The steering-rod, y', (Plate XXVI,) is of light stout tubing fitted at its forward end with a coupling, j, to embrace the piston-rod flange, i, when the Obry gear is entered in place in the torpedo. The shank of the coupling is of square section to work in a guide, z', soldered to the shaft-tube. Between the guide, z', and the after bulkhead stuffing-box, A', the tube is bent to secure the desired alignment, and in the after end of the tube is soldered a small rod, B', forming a continuation of the tube. This rod-extension, B', passes through the stuffing-box and reaches aft within the forward cone of the tail. A thread is cut on the end of the rod-extension, to which fits the threaded sleeve of the rudder-connection, C'. In the after end of the rudder-connection is an eye by which it is connected to the rudder-spindle yoke, D'. The threaded joint of the rod-extension and the rudder-connection permits adjustment of length in the steering-rod by which equal rudder-throw is obtained.

The vertical rudders, E'E', operated by the Obry steering-device, are inserted in the forward top and bottom

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blades, sections of which are cut away for this purpose. The spindles of the rudders work in bearings, F'F', riveted to the blades. The rudder-spindle yoke, D', passing around the shaft of the torpedo, connects the two spindles rigidly together, and at the same time affords a lever-arm to which the rudder-connection is held by a screw.

CARE OF OBRY GEAR.

The Obry gear should be handled with great care to keep it in adjustment and prevent injury to its delicate mechanism. It should be inspected frequently and the steel parts kept free from rust, and well oiled. Particular attention should be paid to the steel centers, and especial care taken that the steel bearings of the gyroscope wheel are kept free from dirt and rust, as either would interfere seriously with the duration of a run of the wheel.

When the Obry gear is not actually in the torpedo, it should be kept in the Obry-gear box, and it is recommended to dismount the gyroscope wheel, and place it in the compartment provided for it, in order that the centers may be easily examined. To dismount the gyroscope wheel, unscrew the after pivot (the one carrying the counter-balance) without disturbing the forward one. Press the position-holder down. The wheel may then be removed. When the wheel is put in again it will only be necessary to screw in the after pivot, finger taut, and the wheel will be in the same adjustment as before removed. The after pivot can usually be turned by the fingers taking hold of the end of the threaded spindle. The jam-nut should be well set up against the counter-weight when correct adjustment is attained, and not disturbed unless absolutely necessary as in making new adjustment on the adjusting-stand. If the jam-nut is well up against the counter-weight, there is no objection to screwing in and

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out the after pivot, by taking hold of both counter-weight and jam-nut with thumb and fingers.

To clean off the pivots and bearings, a small pine stick whittled to a point is recommended. With this, use watch-oil, (a specially prepared porpoise oil for watches and chronometers).

Adjustments of centers, once satisfactorily made, may, in general, be retained, if, in dismounting, care is taken to disturb but one center or adjustment of any pair, leaving the other precisely as found. In re-assembling, set up to the proper fit against the undisturbed center.

If the steering-engine does not work freely and promptly when connected with the rudders, examine the bearings of the steering-rod, rudder-spindles, etc. All these parts Should work very free mechanically. If they stick or bind it will interfere with accurate steering. If these parts are found in good condition the trouble may be sought in the small air and exhaust-ports of the valve-mechanism which may become clogged with dirt. Remove the valve-guard and take out the valve. Clean and wipe well, getting the ports and passages free from obstructions. Hold the valve, if possible, in a strong air-blast from the air-flask or accumulator, to blow out all particles of dust, and, if possible turn such a blast into the valve-plug. Re-assemble and test.

It is thought, a small loose plug of cotton soaked in oil, put in each gyroscope-wheel bearing, when stowed in its compartment in the box, will assist materially in preventing rust.

The tooth engagement between the gyroscope wheel and the impulse-sector must be adjusted properly to the pitch-line. If too close they may bottom, and if not close enough the points will strip and become deformed when the impulse is given. This adjustment (when it becomes

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necessary) is made by raising or lowering the gyroscope in the centers of the vertical axis, about which the outer ring revolves. Following this is the consequent adjustment of the centering-stud in the end of the axle of the gyroscope wheel. This is provided for by adjusting-screws at the extremities of the vertical rock-shaft.

All parts of the Obry gear are a neat fit. Do not attempt to force any part in assembling, dismounting or adjusting; but look for the trouble if parts bind or work too snugly.

The impulse-spring should be kept free from rust by wiping frequently with an oily rag. The spare spring should not be overlooked in this regard.

When the pivots and bearings are perfectly clean, smooth and polished, a gyroscope wheel will run about eleven minutes from the impulse. Very slight imperfections, however, will reduce this time. Six minutes duration is satisfactory for practical purposes, and abundant to control the run of a torpedo.

The depth-index is carried in a body, or casing, a, screwed and riveted to the shell of the torpedo, forward of, and close to, the joint-ring of the immersion-chamber. The parts of the depth-index carried in this body, or casing, are as follows:-

A bevel-worm wheel, b, having a narrow cylinder-face on which the figures 5, 10, 15, 20 are stamped for making the adjustment for depth. A circular ring, or carrier, c, for the bevel-worm wheel, cut as shown in plate to permit meshing of bevel-worm wheel and worm. A small slot is cut on the under edge of this carrier, the slot fitting

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over the pin, x, in the casing, which prevents the axis of the bevel-worm wheel from changing position. A spindle, o, the lower end square, fits in the socket of the adjusting-screw, p, of the diving mechanism. The upper end of the spindle, o, has a square socket fitted to take the, square wrench used in adjusting for depth. It has also a thread tapped in it for the insertion of a removing-tool. Secured to the upper end of the spindle, o, by pin and slot is a cylindrical ring, h, on the outer side of which is cut a thread, which thread forms the worm that turns the bevel-worm wheel.

A clamp-nut, e, screws down far enough to prevent the carrier-ring, c, from rising and thus disengaging the slot on its under side from the pin, x. This clamp-nut has a counter-sunk hole through its center, thus rendering visible the figures on the bevel-worm wheel.

A locking-plug, f, screws down on the spindle, o, pressing it down upon a porpoise-hide washer. The locking-plug serves also to lock the clamp-nut in place.

The reference point of adjustment of the depth-index is for five (5) feet of immersion of the torpedo.

The valve-group differs from previous Marks by carrying an engaging-rod, or shifting-bar, a, whose office is to draw the upper (toothed) end of the rack, c, (replaces old ratchet-bar), into engagement with the teeth of the counter-spindle, d. The after end of the shifting-bar is held in jaws on the upper arm of the bell-crank, which has been lengthened a little for the purpose. The bar lies parallel with the counter-spindle. Its forward end is

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bent downward and carries an easy-fitting sleeve that passes over the end of the counter-spindle.

When the upper arm of the bell-crank is moved aft by the starting-lever, the shifting-bar is drawn aft. The shifting-bar is pushed forward when the friction-roll falls into the blank of the friction-cam at the end of the ruin. The bent arm of the shifting-bar is fitted with a second sleeve to carry a pin with a large disc-like head, called the shifting-bar clutch, b. The extreme forward end of the counter-spindle beyond the teeth is left blank, and upon this blank portion the upper end of the rack habitually rests, held in place between the bent arm of the shifting-bar and the head of the shifting-bar clutch. As the shifting-bar moves aft, actuated by the upper arm of the bell-crank when the starting-lever is thrown back, the rack is drawn into engagement with the teeth of the counter-spindle. At the end of the run the forward motion of the upper arm of the bell-crank disengages the rack, throwing it out upon the blank of the counter-spindle.

To provide against injury in case the teeth of the rack do not mesh immediately upon starting, the shifting-bar clutch has a limited motion between two collar-stops, and the strain is transmitted through a light helical spring around the clutch-pin until, by revolution of the counter-spindle, the engagement of the teeth is effected.

The link that acts to release the spring of the Obry steering-device is attached to the upper arm of the bell-crank, and when this arm is forced aft by the starting-lever the link is pushed aft, and through the action of the push-rod and releasing-lever the spring of the gyroscope is released.

NOTE.-Valve-groups of the 5m. X 45c/m., Mark I, are not interchangeable with those of 3.55m. X 45c/m., Mark

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III, on account of slight necessary difference in the lengths of counter-spindle and shifting-bar, and in the jaws of retarding-lever.

Upon the cylinder of the steering-engine, e, and near its forward end, is cast a lug to which, by means of a bolt and nut, is secured the locking-gear group. The bolt has an enlarged square section abutting against the lug, and from this square part projects an arm at right angles to the bolt. The bolt proper and its arm, cast in one and forming the main bearing, f, constitute the two axes upon which are mounted the various details of gearing and mechanism that control the locking of the torpedo, as regards both the position of the rudder and the duration of locking. The bolt lies fore-and-aft, its arm athwart-ships. Over the arm fits a sleeve, g, having at its inner end the adjustment-cam, and at its outer end an enlarged annular face graduated in accordance with the varying cam radius, and thus available for setting the cam to give the required locked position of the rudder. The zero of this graduation, when in coincidence with the reference mark on the index washer, n, corresponds with the mid-throw of the cam and should indicate the rudder locked horizontal. The enlargement of the sleeve at its outer end and a similar disc-enlargement near the cam, furnish bearings upon which is carried the outer bevel-gear sector, h. The inner, or lock-sleeve, bevel-gear sector, i, revolves about the bolt proper, and carries a small arm to which is pinned the lower end of the rack, c. The two sectors engage by bevel gearing, and when the outer sector is operated by the key the motion is transmitted to the rack

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drawing it down as desired until the requisite length is left to be run up by the teeth of the counter-spindle when the shaft revolves.

Near its outer end the arm is of square section, and beyond the square section it is threaded. Partly countersunk in the end of the sleeve, and secured by means of the square section and the threaded part of the arm, is a series of washers and nuts-index-washer, n, locking-adjustment index, o, clamp-nut, p, and lock-nut, q, by which both the position and duration of locking are fully controlled and operated independently of each other. The ends of the cylindrical pieces, with the washers and nuts, constitute the locking-dial upon which the adjustments are made by the locking-key. The dial is readily accessible through an opening cut in the shell of the torpedo.

The bolt proper, carries next to the arm a small cylinder, k, called the locking-bar slide block, fitted at the after end to receive the action of the adjustment-cam, by which it is caused to move forward as the increasing cam radius operates against it. The forward end of this cylinder bears against the bottom of a sleeve, m, called the lock-sleeve, which thus has also longitudinal motion along the bolt from the action of the cam.

A spring in the sleeve, held by a washer and nut on the end of the bolt, forces back both the sleeve and cylinder against the cam.

The end of the lock-sleeve, next the cylinder, has a bell-mouthed flange, and to the cylinder is pivoted a ring carrying two arms, 180° apart, called the locking-bar, l, so adjusted that pressure of the spring in the sleeve causes the bell-mouthed flange to bear equally upon the two arms of the ring. One arm of the ring is extended and by jaws and pins is attached to the valve-rod of the

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steering-engine. Two slotted portions are cut in the flange of the lock-sleeve, and when, by rotation of the sleeve on its axis, the slotted portions come opposite the arms of the ring, the ring is then free to turn on its pivots and offers no more resistance to the operation of the valve. This is the unlocked position, and the steering-mechanism has full control. When the flanged portions bear against the arms of the ring they are held rigid, and thus prevent motion of the valve-rod although the pendulum and hydrostatic-piston may be exerting their full force upon it. This is the locked position, and the steering-mechanism is inoperative. The forward end of the lock-sleeve is slotted to receive the arm of the inner bevel-gear sector.

This arrangement compels the inner bevel-gear sector and lock-sleeve always to rotate together, controlling the locking and its duration; but the lock-sleeve in its fore-and-aft motion is independent of the sector, and thus the position of the rudder while locked is controlled.

The valve-rod is connected with the rock-shaft rod projecting through the bulkhead of the immersion-chamber by a square-headed pointed screw accessible from the outside (underneath) through a hole in the shell. Just abaft this connecting-screw the valve-rod has an adjustable union, its adjusting-screw being reached through a hole in the side of the torpedo. This adjustable union is for lengthening or shortening the valve-rod, thus taking the place of the valve-star of 3.55m. X 45c/m., Marks I and II torpedoes, and consists of the bell-crank, r, the bell-crank cross-head, s, the adjusting-screw, t, adjustment bracket, u, and spiral-spring, v.

To lengthen the valve-rod, turn the adjustment-screw of the union to the right; to shorten, to the left. To lock the rudder: the rudder should be horizontal when the zero mark of the adjustment-cam sleeve is in coincidence with the

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reference mark on the index-washer; to lock the rudder up, turn the cam-sleeve to the left; to lock the rudder down, turn the cam-sleeve to the right.

To lock the steering-engine; turn the locking-adjustment index to the left the desired number of graduations and clamp it, and then with the locking-key turn the outer bevel-gear sector to the left until the key brings up against the index.

In these Marks the piston has but three (3) ribs, without packing-rings. The description, (p. 30, Whitehead Torpedo, U. S. N., 45c/m., Mark I. The steering-engine, Plate XIII), already issued to the service, applies to the 3.55m. X 45c/m., Mark I, alone. Those portions of the text that do not entirely apply to the steering-engine of the 3.55m. X 45c/m., Mark III, and 5m. X 45c/m. Mark I, are the following:- P. 30, near middle [the valve is connected --- and the locking-jaws, m',]; p. 32, [the piston is packed in the cylinder in the faces of the ribs]; p. 32, [the valve is packed by oil --- through a hole in the shell]; p. 32 et seq., [rigidly attached to the valve-rod, f, --- accidental change of this adjustment].

The passages indicated in the brackets relate to the union, g, the locking-jaws, m', the bronze spring packings, and the valve-star, o, which details are eliminated or modified in the new Marks (3.55m. X 45c/m., Mark III, and 5m. X 45c/m, Mark I).

make a substantial joint-ring that fits over and against a corresponding joint-surface worked on the rear face of the after-body joint-ring. Eight (8) steel joint-screws, uniformly spaced, secure the two parts together. The forward cone is fitted as a gear-box and contains the bevel-gears that transmits the revolutions to the forward propeller.

The propeller-shaft, in two sections, is coupled in the wake of the tail-joint. The after section fits as a sleeve over the forward one, and is held to revolution with it by four feathers and slots. The forward gear of the bevels is forged in one with the after section of the shaft.

When the Obry steering-rod is disconnected, the screw is habitually entered in the locking hole of the tail-cone to lock the rudder-yoke, and thus hold the vertical rudders amidships.

DIMENSIONS, WEIGHTS, ETC.

The 3.55m. x 45c/m., Mark III, has the same exterior dimensions as the earlier Marks, and approximately the same total weight, weight of charge, etc. (It has not as yet been finally ballasted for trim and stability but has about 11 lbs. negative buoyancy when fully charged and ready for launching.

The 5m. X 45c/m. Mark I, is longer and heavier, and carries a larger charge. The weight of charge is 220 lbs. Capacity of air-flask, 9.9 cu. ft. Weight of air at 62° F. when compressed to 1350 lbs. pressure per sq. in., 69.19 lbs. Weight of Obry gear, (removable part represented by dummy), or weight of dummy, 8 lbs. 6 ozs. Total weight of torpedo with war-head attached, air-flask charged to 1350 lbs. pressure, and all ready for launching, 1161 lbs. (approx.). Buoyancy (approx.), 1/2 lb.

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SPECIAL PRECAUTIONS CONCERNING
OBRY GEAR.

Attention is called to a danger in the use of the Obry gear, if special care is not exercised to prevent it. As is the case with the depth-controlling mechanism, so with the Obry gear, the presence of dirt or foreign matter in the valves, or the rusting of the rudders or rudder connections will render the gear inoperative. It will be quite evident that should this occur, the vertical rudders being held permanently hard over to one side or the other, the torpedo will steer continuously in one direction to the right or left.

While failure of the depth-mechanism to act may result in the loss of the torpedo or an ineffective shot, it cannot endanger the vessel from which the torpedo is discharged or friendly vessels out of the line of fire, whereas failure of the Obry gear to act may so endanger them.

It is, therefore, very essential that before discharging the torpedo with a war charge, the reducing-valve and controlling-valve and passages of the Obry gear shall be known to work freely and not rendered inoperative through the presence of dirt, verdegris, or gumming oil, and that the rudders are in perfectly free working order, and not cramped by rust or from the packing around the rudder-rod being set up too tight.

Before the importance of this was fully realized some erratic shots were made, due to the above causes.

Great care shall be taken that the controlling-valve is clean, for if any dirt gets in it and chokes one of the airports, the torpedo will run in a curve and may come back to the point of firing.

The adjustments of the Obry, made at Sag Harbor,

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will be difficult to recover, without running the torpedo again, if any changes are made in the following:-

The position of the nut and jamb-nut (forming the counter-balance) on the after centering-screws of the gyroscope wheel.